"By my father and by my mother." He said: "Allah forbids you to swear by your forefathers." 'Umar said: "By Allah, I never swore by them again, whether saying it for myself or reporting it of others."
أَنَّهُ سَمِعَ النَّبِيُّ ﷺ عُمَرَ مَرَّةً وَهُوَ يَقُولُ وَأَبِي وَأَبِي فَقَالَ إِنَّ اللَّهَ يَنْهَاكُمْ أَنْ تَحْلِفُوا بِآبَائِكُمْ فَوَاللَّهِ مَا حَلَفْتُ بِهَا بَعْدُ ذَاكِرًا وَلاَ آثِرًا