Look not a gift horse in the mouth.

Do not scrutinize a present so critically that you seem ungrateful for receiving it. The proverb advises accepting a freely given benefit without dwelling on its defects, quality, or monetary value.

The image refers to examining a horse's teeth to judge its age and condition. Figuratively, it contrasts a gift with a purchase, but does not discourage reasonable questions about safety, suitability, hidden costs, or obligations attached to an offer.

Use it to gently reproach excessive fault-finding about a genuine present, favor, or unexpected advantage, especially when someone focuses on shortcomings rather than generosity. It is not apt for dismissing reasonable concerns about safety, suitability, hidden costs, or conditions attached to an offer.