John Gill Commentary Deuteronomy 18:9

"When thou art come into the land which Jehovah thy God giveth thee, thou shalt not learn to do after the abominations of those nations." — Deuteronomy 18:9 (ASV)

When you are come into the land which the Lord your God gives
you
The land of Canaan, often thus described, to express the goodness of God in bestowing it on them, as a mere favour of his, without any desert of theirs; and so typical of the heavenly Canaan, or eternal life, which is the free gift of God through Christ:

you shall not learn to do after the abominations of these nations ;
the seven nations which before inhabited it; they might learn, as Jarchi observes, to know how corrupt their works were, and to show to their children, that they might not do so; but they were not to learn them so as to practise them, but to have them in the utmost abhorrence, as being abominable to God, and which should be so to them; some of which are as follow.