The question of why does God hear our prayers? There is obviously no obligation in God to hear prayer: God is under no duty to the creature. The creature cannot compel God to hear prayer. The prayers of human beings in the course of history have raised in number of absurd, wicked, hurtful prayers. 

In Psalm 68:18, the Psalmist writes, “If I regard iniquity in my heart, the lord will not hear me.” In Proverbs 1, Wisdom warns that the one who will not regard wisdom will not be heard when he prays having suffered the result of refusing wisdom:

Proverbs 1:24–33 (AV)

24 Because I have called, and ye refused; I have stretched out my hand, and no man regarded; 25 But ye have set at nought all my counsel, and would none of my reproof: 26 I also will laugh at your calamity; I will mock when your fear cometh; 27 When your fear cometh as desolation, and your destruction cometh as a whirlwind; when distress and anguish cometh upon you. 28 Then shall they call upon me, but I will not answer; they shall seek me early, but they shall not find me: 29 For that they hated knowledge, and did not choose the fear of the LORD: 30 They would none of my counsel: they despised all my reproof. 31 Therefore shall they eat of the fruit of their own way, and be filled with their own devices. 32 For the turning away of the simple shall slay them, and the prosperity of fools shall destroy them. 33 But whoso hearkeneth unto me shall dwell safely, and shall be quiet from fear of evil.

So we see that the matter of being heard is not automatic. Why then does God hear prayer?

Sibbes gives two reasons: (1) the good in our prayer has been brought about by the action of the Spirit; and (2) God receives as he has chosen us in election. It is God’s good grace toward us, to choose us and to transform us that is the basis for God hearing us.

First: the operation of God

Now God hears our prayers, First, Because the materials of these holy desires are good in themselves, and from the person from whence they come, his beloved spouse, as it is in Cant. 2:14, where Christ, desiring to hear the voice of his church, saith, ‘Let me see thy countenance, and let me hear thy voice; for sweet is thy voice, and thy countenance is comely.’ Thus the voice of the Spouse is sweet, because it is stirred up by his own Spirit, which burns the incense, and whence all comes which is savingly good. This offering up of our prayers in the name of Christ, is that which with his sweet odours perfumes all our sacrifices and prayers; because, being in the covenant of grace, God respects whatsoever comes from us, as we do the desires of our near friends, Rev. 8:3.

Second, God receives us in the relationship which He has chosen for us:

And then, again, God hears our prayers, because he looks upon us as we are in election, and choice of God the Father, who hath given us to him. Not only as in the near bond of marriage, husband and wife, but also as he hath given us to Christ; which is his plea unto the Father, John 17:6, ‘Thine they were, thou gavest them me,’ &c. The desires of the church please him, because they are stirred up by his Spirit, and proceed from her that is his; whose voice he delights to hear, and the prayers of others for his church are accepted, because they are for her that is his beloved.

And further:

To confirm this further, see Isa. 58:9. ‘Thou then shalt cry, and the Lord shall answer; thou shalt call, and presently he shall say, Here I am,’ &c. So as soon as Daniel had ended that excellent prayer, the angel telleth him, ‘At the beginning of thy supplications the decree came forth,’ &c., Dan. 9:23. So because he knows what to put into our hearts, he knows our desires and thoughts, and therefore accepts of our prayers and hears us, because he loves the voice of his own Spirit in us. So it is said, ‘He fulfils the desires of them that fear him; and he is near to all that call upon him, to all that call upon him in truth,’ Ps. 145:18. And our Saviour, he saith, ‘Ask and ye shall receive,’ &c., Mat. 7:7. So we have it, 1 John 5:14, ‘And we know if we ask anything according to his will, he heareth us.’

First: 

Use 1. Let it therefore be a singular comfort to us, that in all wants, so in that of friends, when we have none to go to, yet we have God, to whom we may freely pour out our hearts. There being no place in the world that can restrain us from his presence, or his Spirit from us, he can hear us and help us in all places. What a blessed estate is this! None can hinder us from driving this trade with Christ in heaven.

I was told by a woman that when she was a child, she was told by an adult, I do not love you. The little girl thought to herself, that is okay. Jesus loves me.

Second, when stop realize what a privilege it is to go to God in prayer, it should stir up our hearts to make use of the privilege:

Use 2. And let us make another use of it likewise, to be a means to stir up our hearts to make use of our privileges. What a prerogative is it for a favourite to have the fare* of his prince! him we account happy. Surely he is much more happy that hath God’s care, him to be his father in the covenant of grace; him reconciled, upon all occasions, to pour out his heart before him, who is merciful and faithful, wise and most able to help us. ‘Why are we discouraged, therefore; and why are we cast down,’ Ps. 42:11, when we have such a powerful and such a gracious God to go to in all our extremities? He that can pray can never be much uncomfortable.

And three: 

Use 3. So likewise, it should stir us up to keep our peace with God, that so we may always have access unto him, and communion with him. 

But this is a privilege which can be lost:

What a pitiful case is it to lose other comforts, and therewith also to be in such a state, that we cannot go to God with any boldness! It is the greatest loss of all when we have lost the spirit of prayer; for, if we lose other things, we may recover them by prayer. But when we have lost this boldness to go to God, and are afraid to look him in the face, as malefactors the judge, this is a woful state.

Sibbes then considers two things which will break the fellowship with God which makes prayer possible. First, there is unrepentant sin:

Now there are diverse cases wherein the soul is not in a state fit for prayer. As that first, Ps. 66:18, ‘If I regard iniquity in my heart, the Lord will not regard my prayer.’ If a man hath a naughty heart, that purposeth to live in any sin against God, he takes him for an enemy, and therefore will not regard his prayer. Therefore we must come with a resolute purpose to break off all sinful courses, and to give up ourselves to the guidance of God’s Spirit. And this will be a forcible reason to move us thereunto, because so long as we live in any known sin unrepented of, God neither regards us nor our prayers. What a fearful estate is this, that when we have such need of God’s favour in all estates; in sickness, the hour of death, and in spiritual temptation, to be in such a condition as that we dare not go to God! Though our lives be civil,* yet if we have false hearts that feed themselves with evil imaginations, and with a purpose of sinning, though we act it not, the Lord will not regard the prayers of such a one; they are abominable. The very ‘sacrifice of the wicked is abominable,’ Prov. 15:8.

The second is a refusal to forgive:

Another case is, when we will not forgive others. We know it is directly set down in the Lord’s prayer, ‘Forgive us our trespasses, as we forgive them that trespass against us,’ Mat. 6:14; and there is further added, ver. 15, ‘If you forgive not men their trespasses, neither will your heavenly Father forgive you.’ If our hearts tell us we have no disposition to pardon, be at peace and agreement, then we do but take God’s name in vain when we ask him to forgive our sins, and we continue in envy and malice. In this case God will not regard our prayers, as it is said, ‘I care not for your prayers, or for any service you perform to me,’ Isa. 1:15. Why? ‘For your hands are full of blood,’ Isa. 66:1. You are unmerciful, of a cruel, fierce disposition, which cannot appear before God rightly, nor humble itself in prayer. If it doth, its own bloody and cruel disposition will be objected against the prayers, which are not mingled with faith and love, but with wrath and bitterness. Shall I look for mercy, that have no merciful heart myself? Can I hope to find that of God, that others cannot find from me? An unbroken disposition, which counts ‘pride an ornament,’ Ps. 73:6, that is cruel and fierce, it cannot go to God in prayer. For, whosoever would prevail with God in prayer must be humble; for our supplications must come from a loving, peaceable disposition, where there is a resolution against all sin, Ps. 73:1. Neither is it sufficient to avoid grudging and malice against these, but we must look that others have not cause to grudge against us, as it is commanded: ‘If thou bring thy gifts to the altar, and there rememberest that thy brother hath ought against thee; leave there thy gift before the altar, and go thy way; first be reconciled to thy brother, and then come and offer thy gift,’ Mat. 5:23. So that if we do not seek reconciliation with men unto whom we have done wrong, God will not be reconciled to us, nor accept any service from us.

There is another reference to the result of a failure to forgive spoken of by Jesus in Matthew 18. In the parable of the unforgiving servant, Jesus tells of a servant who was forgiven much but he himself would not forgive another slave who owed him just a little:

21 Then came Peter to him, and said, Lord, how oft shall my brother sin against me, and I forgive him? till seven times? 22 Jesus saith unto him, I say not unto thee, Until seven times: but, Until seventy times seven. 23 Therefore is the kingdom of heaven likened unto a certain king, which would take account of his servants. 24 And when he had begun to reckon, one was brought unto him, which owed him ten thousand talents. 25 But forasmuch as he had not to pay, his lord commanded him to be sold, and his wife, and children, and all that he had, and payment to be made. 26 The servant therefore fell down, and worshipped him, saying, Lord, have patience with me, and I will pay thee all. 27 Then the lord of that servant was moved with compassion, and loosed him, and forgave him the debt. 28 But the same servant went out, and found one of his fellowservants, which owed him an hundred pence: and he laid hands on him, and took him by the throat, saying, Pay me that thou owest. 29 And his fellowservant fell down at his feet, and besought him, saying, Have patience with me, and I will pay thee all. 30 And he would not: but went and cast him into prison, till he should pay the debt. 31 So when his fellowservants saw what was done, they were very sorry, and came and told unto their lord all that was done. 

What then was the result for the one who refused to forgive:

32 Then his lord, after that he had called him, said unto him, O thou wicked servant, I forgave thee all that debt, because thou desiredst me: 33 Shouldest not thou also have had compassion on thy fellowservant, even as I had pity on thee? 34 And his lord was wroth, and delivered him to the tormentors, till he should pay all that was due unto him. 35 So likewise shall my heavenly Father do also unto you, if ye from your hearts forgive not every one his brother their trespasses.

Matthew 18:21–35 (AV). The man was delivered to tormentors until he would forgive. The lord would not hear the prayer of the servant who would not forgive. This is the most dreadful of states.

Sibbes then finishes with an interesting question: How do I know if God hears my prayer?

Quest. How shall I know whether God regard my prayers or not?

Ans. 1. First, When he grants the thing prayed for, or enlargeth our hearts to pray still. It is a greater gift than the thing itself we beg, to have a spirit of prayer with a heart enlarged; for, as long as the heart is enlarged to prayer, it is a sign that God hath a special regard of us, and will grant our petition in the best and fittest time.

2. When he answers us in a better and higher kind, as Paul when he prayed for the taking away of the prick of the flesh, had promises of sufficient grace, 2 Cor. 12:7–9.

3. When, again, he gives us inward peace, though he gives not the thing, as Phil. 4:6, ‘In nothing be careful, but in all things let your requests be made to God with prayer and thanksgiving.’

Obj. But sometimes he doth not answer our requests.

Ans. It is true he doth not, but ‘the peace of God which passeth all understanding guards our hearts and minds in the knowledge and love of God,’ Philip. 4:7. So though he answers not our prayers in particular, yet he vouchsafes inward peace unto us, assuring us that it shall go well with us, though not in that particular we beg. And thus in not hearing their prayers, yet they have their hearts’ desire when God’s will is made known. Is not this sufficient for a Christian, either to have the thing, or to have inward peace, with assurance that it shall go better with them than if they had it; with a spirit enlarged to pray, till they have the thing prayed for. If any of these be, God respects our prayers.