عَنِ ابْنِ عُمَرَ رَضِيَ اللَّهُ عَنْهُمَا أَكْثَرُ مَا كَانَ النَّبِيُّ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يحلف: «لَا ومقلب الْقُلُوب» . رَوَاهُ البُخَارِيّ

He reported God’s Messenger as saying, “God forbids you to swear by your fathers. If anyone swears he must swear by God, or keep silent.” (Bukhari and Muslim.)