Matthew Poole and continuators on Jeremiah 3:21

21 A voice was heard upon the high places , weeping and supplications of the children of Israel : for they have perverted their way, and they have forgotten the LORD their God?

Here the Prophet seems to express Israels Repentance, and turning to God, and that, which they were at present ingaging themselves in, (the word being participial and in the present tense) delivered in a prophetical stile as that in chap. 31.15. and that not only out of a sense of their judgements, that they were under, but chiefly of their sins, they were guilty of, and the pardon of which they were now begging, which is intimated by weeping, and supplication.

Viz. That their cry might be the more publique, both open, and loud chap. 22.20. and Matth. 10.27. possibly alluding to the usual practice, of praying on the tops of houses in great calamities, Isa. 15.3. and 22.1. Ier. 7.29.

Or rather weeping supplications shewing the intenseness of it, praying in weeping, and weeping in prayer, Zech. 12.10. like Peters weeping Matth. 26.75.

The end of which might be to provoke Iudah also to Repentance, or otherwise to charge upon them their stupidity, and threaten them with the like judgments, if they would not return upon Israels example.