大公无私
The balance distinguishes not between gold and lead.

eg：A good boss should deal with all workers in fair field and no favour.

中英俚语俗语来源：龚自珍·龚定庵集·论：“且今之大公无私者，有杨墨之贤邪。”

同义词：舍己为人 To bell the cat.
反义词：假公济私 To practise jobbery.