斤斤计较-----strain at a gnat

例句：
A: Tom is a cheapskate. I treated him a helping of roast beef, but he bought me a coke.
汤姆真小气。我请他吃牛排，但是他只请我喝可乐。
B: Forget it! Don't strain at a gnat. As you know，he is hard np these days.
算了吧！不要斤斤计较。如你所知，他最近手头紧。

同义词：
look at both sides of a penny
skin a flint