Ben Sira 12:10

10 Never trust thine enemy: for like as iron rusteth, so is his wickedness.

Ben Sira 12:10 In-Context

8 A friend cannot be known in prosperity: and an enemy cannot be hidden in adversity.
9 In the prosperity of a man enemies will be grieved: but in his adversity even a friend will depart.
10 Never trust thine enemy: for like as iron rusteth, so is his wickedness.
11 Though he humble himself, and go crouching, yet take good heed and beware of him, and thou shalt be unto him as if thou hadst wiped a lookingglass, and thou shalt know that his rust hath not been altogether wiped away.
12 Set him not by thee, lest, when he hath overthrown thee, he stand up in thy place; neither let him sit at thy right hand, lest he seek to take thy seat, and thou at the last remember my words, and be pricked therewith.
The King James Version is in the public domain.