Charles Ellicott Commentary Exodus 34:12-16

"Take heed to thyself, lest thou make a covenant with the inhabitants of the land whither thou goest, lest it be for a snare in the midst of thee: but ye shall break down their altars, and dash in pieces their pillars, and ye shall cut down their Asherim; for thou shalt worship no other god: for Jehovah, whose name is Jealous, is a jealous God: lest thou make a covenant with the inhabitants of the land, and they play the harlot after their gods, and sacrifice unto their gods, and one call thee and thou eat of his sacrifice; and thou take of their daughters unto thy sons, and their daughters play the harlot after their gods, and make thy sons play the harlot after their gods." — Exodus 34:12-16 (ASV)

This passage may be compared with Exodus 23:24-25; Exodus 23:32–33. It repeats, with some enlargements, the enactments there made, and traces in detail the evil consequences which would follow from a neglect of the enactments.