Full Sharh — Bulugh al-Maram 1556
عَنْ اِبْنِ عُمَرَ رَضِيَ اَللَّهُ عَنْهُمَا, { عَنْ رَسُولِ اَللَّهِ - صلى الله عليه وسلم -أَنَّهُ أَدْرَكَ عُمَرَ بْنَ اَلْخَطَّابِ فِي رَكْبٍ, وَعُمَرَ يَحْلِفُ بِأَبِيهِ, فَنَادَاهُمْ رَسُولُ اَللَّهِ - صلى الله عليه وسلم - "أَلَا إِنَّ اَللَّهَ يَنْهَاكُمْ أَنْ تَحْلِفُوا بِآبَائِكُمْ, فَمَنْ كَانَ حَالِفاً فَلْيَحْلِفْ بِاَللَّهِ, أَوْ لِيَصْمُتْ" } مُتَّفَقٌ عَلَيْهِ 1 .1 - صحيح. رواه البخاري ( 6646 )، ومسلم ( 1646 ) ( 3 ).
English Translation
Narrated Ibn 'Umar (RA):: Allah's Messenger (ﷺ) overtook 'Umar bin al-Khattab when he was with a party of riders of about ten and 'Umar was swearing by his father. Allah's Messenger (ﷺ) called them and said, "Verily! Allah forbids you from swearing by your fathers. Therefore, if anyone swears, he must swear by Allah or keep silent."
Source
Bulugh al-Maram(بلوغ المرام)
Oaths and Vows
Hadith Number
1556