Jeremiah 18:15

Because my people hath forgotten me, they have burned incense to vanity, and they have caused them to stumble in their ways from the ancient paths, to walk in paths, in a way not cast up;

Because my people hath forgotten me,.... Or, "that they have forgotten me" {z}; this is the horrible thing they have done, which was unheard of among the Gentiles, who were always tenacious of their gods, and the worship of them; and that foolish and unwise thing, which was like leaving pure flowing streams of water for dirty puddles. This is to be understood of their forsaking the worship of God, as the Targum interprets it, and following after idols:

they have burnt incense to vanity; to idols, which are vain empty things, and which cannot give their worshippers what they expect from them: or, "in vain they burn incense" {a}; even to the true God, while they also sacrificed unto idols; which to do was an abomination to the Lord, Isaiah 1:13; and especially burning incense to idols must be a vain thing; and so the Targum,

"to no profit a they burn incense or spices:''

and they have caused them to stumble in their ways; that is, either the idols they worshipped, or the false prophets caused the professing people of the Jews to stumble and fall in the ways into which they led them: and

from the ancient paths; or, "the paths of eternity" {b}; which lead to eternal life; or which were of old marked out by the revealed will of God for the saints to walk in; and in which the patriarchs and people of God, in all former ages, did walk; and which were appointed from everlasting, and will remain for ever; and these are the good old paths in Jeremiah 6:16;

to walk in paths, in a way not cast up; a new way, unknown in former times; an unbeaten track, which the saints had never walked in; a rough path, unsafe and dangerous; and hence they stumbled, and fell, and came to ruin; as follows:

{z} ynxkv yk "quod obliti sunt", Schmidt.
{a} wrjqy awvl "frustra adolebunt, vel adolent", Pagninus, Calvin.
{b} Mlwe ylybv "semitae quae a seculo, seu antiquo", vid. Schmidt; so Targum; "semitis jam olim praescriptis", Piscator.