John Gill

O my mountain in the midst of the field,.... Meaning either the temple, called the mountain of the house, and of the Lord's house, Mic 3:12, or else Jerusalem, which stood on a hill in the midst of a plain, surrounded with fruitful fields and gardens; or in the midst of a land like a field. The Targum is, "because thou worshippest idols upon the mountains in the field:'' I will give thy substance and all thy treasures to the spoil; all the riches of the city and temple to be the spoil and plunder of the enemy; See Gill on Jer 15:13. and thy high places for sin, throughout all thy borders. The sense is, that all their substance and treasure throughout their borders, the riches of the whole land, as well as of the city and temple, Jer 15:13 and all their high places throughout the land, which were used for sin, for idolatrous practices, on account thereof, should become the spoil of the enemy.