Deuteronomy 20:18

18 that they may not teach you to do all their abominations, which they did to their gods, and ye should sin before the Lord your God.

Deuteronomy 20:18 In-Context

16 ye shall not take any thing alive;
17 but ye shall surely curse them, the Chettite, and the Amorite, and the Chananite, and the Pherezite, and the Evite, and the Jebusite, and the Gergesite; as the Lord thy God commanded thee:
18 that they may not teach you to do all their abominations, which they did to their gods, and ye should sin before the Lord your God.
19 And if thou shouldest besiege a city many days to prevail against it by war to take it, thou shalt not destroy its trees, by applying an iron tool to them, but thou shalt eat of it, and shalt not cut it down: Is the tree that is in the field a man, to enter before thee into the work of the siege?
20 But the tree which thou knowest to be not fruit-bearing, this thou shalt destroy and cut down; and thou shalt construct a mound against the city, which makes war against thee, until it be delivered up.

The Brenton translation of the Septuagint is in the public domain.