حَدَّثَنَا عَبْدُ الرَّزَّاقِ، حَدَّثَنَا مَعْمَرٌ، عَنِ الزُّهْرِيِّ، عَنْ سَالِمٍ، عَنْ أَبِيهِ، عَنْ عُمَرَ
رَضِيَ اللَّهُ عَنْهُ قَالَ سَمِعَنِي رَسُولُ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ وَأَنَا أَحْلِفُ، بِأَبِي فَقَالَ: إِنَّ اللَّهَ يَنْهَاكُمْ أَنْ تَحْلِفُوا بِآبَائِكُمْ قَالَ عُمَرُ فَوَاللَّهِ مَا حَلَفْتُ بِهَا بَعْدُ ذَاكِرًا وَلَا آثِرًا
The Messenger of Allah (sallallahu alayhi wa sallam) heard me swearing an oath by my father and said: “Allah forbids you to swear by your fathers.” Umar said: By Allah, I never swore by my father after that, whether saying it myself or narrating what someone else had said.
Musnad Ahmad 233, Book 2, Musnad `Umar b. al-Khattab (ra), Hadith 156. 1 min read