not harm a hair on (one's) head

not harm a hair on (one's) head

To not hurt or injure someone in even the slightest degree. They had better not harm a hair on your head, I'll go to the police straight away!

See also: hair, harm, head, not, on

not harm a hair of someone's head

not cause someone the slightest harm.

See also: hair, harm, head, not, of