Explaining "Never look a gift horse in the mouth"

What does it mean?

The phrase means you should not criticize or inspect a gift or favor too closely, as it may appear ungrateful.

Tone

Origin

The origin comes from the practice of evaluating a horse's age and health by looking at its teeth. When receiving a horse as a gift, it would be impolite to inspect its mouth this way, as it suggests distrust or lack of appreciation.