The best equivalent I know is to split hairs:

to argue about whether details that are not important are exactly correct
_- 'She earns three time what I earn.'

• 'Actually, it's more like two and a half.'
• 'Oh stop splitting hairs!'_

There's also the verb quibble:

to argue or complain about small, unimportant things

But it's not figurative.

_{Please note that the literal translation of to split hairs works as an idiom in Farsi too, but it doesn't mean the same thing as the English idiom. In Farsi to split hairs means something like to have a discerning razor-sharp mind, and shows approval.}

Consider split hairs:

to argue about whether details that are not important are exactly correct
_- 'She earns three time what I earn.'

• 'Actually, it's more like two and a half.'
• 'Oh stop splitting hairs!'_

There's also the verb quibble, but it's not figurative.:

to argue or complain about small, unimportant things

_{Please note that the literal translation of split hairs works as an idiom in Farsi too, but it doesn't mean the same thing as the English idiom. In Farsi split hairs means something like have a discerning razor-sharp mind, and shows approval.}