כִּ֛י בָּ֥א הַחֲל֖וֹם בְּרֹ֣ב עִנְיָ֑ן
For comes the dream by means of/in much busyness.
“The use of the article is generic” (Longman, 149).
The beth marks the means of causation for the dreams:
3. Realizes an action by indicating one of the following:
(i) Instrument—the so-called beth instrumenti
a. Non-human instrument
בַּשֵּׁבֶט יַכּוּ עַל־הַלְּחִי
אֵת שֹׁפֵט יִשְׂרָאֵל׃
With a rod they strike upon the cheek the ruler of Israel (Mic. 4:14).
Christo Van der Merwe, Jackie Naudé, Jan Kroeze et al., A Biblical Hebrew Reference Grammar, electronic ed. (Sheffield: Sheffield Academic Press, 1999), 281-82.
Seow translates busyness as “preoccupation”. He notes that the noun only occurs in Ecclesiastes. In post-biblical Hebrew it “has the nuance of something that causes anxiety” (Seow, 121).
וְק֥וֹל כְּסִ֖יל בְּרֹ֥ב דְּבָרִֽים
And the voice of a fool in many words.