expression, godan verb (-u)
grumble about trivial things; complain over nothing
Used when someone complains or makes a fuss about something minor or unimportant. Often implies the speaker finds the complaint unreasonable.
彼はいつも四の五の言ってばかりで、仕事が進まない。
He's always grumbling about trivial things, so the work doesn't progress.
四の五の言
Stop complaining and just get it done.