Proverbs 26:2 (ESV)

2 Like a sparrow in its flitting, like a swallow in its flying, a curse that is causeless does not alight.

An undeserved curse will not come to pass, just as a fluttering bird will not stay in one place. A classic example is the story of Balaam, who had to say, “How can I curse those whom God has not cursed? How can I denounce those whom the Lord has not denounced?” (Numbers 23:8).

This proverb rejects a superstitious view of curses, whereby they are viewed as magical things with power in themselves.