look a gift horse in the mouth

Fig. to be ungrateful to someone who gives you something; to treat someone who gives you a gift badly. (Usually with a negative.) Never look a gift horse in the mouth. I advise you not to look a gift horse in the mouth.

to criticize or refuse to take something that has been offered to you I know the car's not in great condition, but you shouldn't look a gift horse in the mouth.

if someone tells you not to look a gift horse in the mouth, they mean that you should not criticize or feel doubt about something good that has been offered to you Okay, it's not the job of your dreams but it pays good money. I'd be inclined not to look a gift horse in the mouth if I were you.

Be critical or suspicious of something received at no cost. For example, Dad's old car is full of dents, but we shouldn't look a gift horse in the mouth. This term, generally expressed as a cautionary proverb ( Don't look a gift horse in the mouth), has been traced to the writings of the 4th-century cleric, St. Jerome, and has appeared in English since about 1500. It alludes to determining the age of a horse by looking at its teeth.

To be critical or suspicious of something one has received without expense.