Lay a finger on somebody

Pro Tip 1/3

Conflict Avoidance

Used when promising not to start or engage in physical conflict.

I said I wouldn't lay a finger on him, and I meant it.

Pro Tip 2/3

Immediate Threat

Can imply the immediate possibility of physical harm.

If you lay a finger on me, I'll call the police.

Pro Tip 3/3

Protective Warning

Often used by someone warning others to not harm a person or animal.

Lay a finger on my brother and you'll have me to answer to!