23 إنَّ الله يَنْهَاكُمْ أَنْ تَحْلِفُوا بِآبَائِكُمْ
Indeed, Allah forbids you to swear by your forefathers.

عن عمر بن الخطاب رضي الله عنه قال: قَالَ رَسُولُ الله صلى الله عليه وسلم : «إنَّ الله يَنْهَاكُمْ أَن تَحْلِفُوا بِآبَائِكم». وَلمسلم: «فَمَن كان حَالِفا فَلْيَحْلِف بِالله أو لِيَصْمُت». وَفِي رِوَايَةٍ قَالَ عُمَرُ رضي الله عنه قال: «فَوَالله ما حَلَفْتُ بِهَا منذ سَمِعْت رَسُولَ الله يَنْهَى عَنْهَا، ذَاكراً وَلا آثِراً».

‘Umar ibn al-Khattāb (may Allah be pleased with him) reported that the Messenger of Allah (may Allah’s peace and blessings be upon him) said: "Indeed, Allah forbids you to swear by your forefathers." In a narration by Muslim: "If anyone should swear, let him swear by Allah or keep silent." In another narration, ‘Umar (may Allah be pleased with him) added: "By Allah! I have never sworn by that since I heard the Prophet (may Allah’s peace and blessings be upon him) forbid it, neither by saying it myself, nor by reporting it from others."

صحيح - ( متفق عليه ). Sahih/Authentic. [Al-Bukhari and Muslim]

سمِع رسولُ الله صلى الله عليه وسلم عمرَ رضي الله عنه وهو يَحْلِفُ بِأَبيه فَنَادَاهم النَّبي صلى الله عليه وسلم رافِعَاً صَوْتَه:«إنَّ الله يَنْهَاكُمْ أَنْ تَحْلِفُوا بِآبَائِكُمْ» فَامْتَثَلَ الصَّحَابَةُ أَمْرَ رَسُولِ اللهِ صلى الله عليه وسلم وَأَصْبحُوا لا يَحلِفُون إلا بالله، حتَّى ذكر عُمَرُ أنَّه لم يحلِف بغير الله منذُ سَمع رسولَ الله- صلى الله عليه وسلم – ينهى عن ذلك، لا مُتعمِّداً ولا ناقِلاً لحلِف غيرِه بغيرِ الله .
The Messenger of Allah (may Allah’s peace and blessings be upon him) heard ‘Umar ibn al-Khattāb (may Allah be pleased with him) swear by his father. Thereupon, he called out the Companions and said loudly: "Indeed, Allah forbids you to swear by your forefathers." The Companions (may Allah be pleased with them) immediately complied and stopped swearing by other than Allah, the Almighty. Later, ‘Umar (may Allah be pleased with him) emphasized that he never swore by other than Allah, the Almighty, ever since he heard the prohibition, neither by taking such an oath intentionally by himself, nor by reporting it on behalf of others.

تحْريمُ الحلِف بغيرِ الله وخصَّ الحلِف بِالآباء لأنَّه من عاداتِ الجَاهِلِيةِ مَنْ أَرَادَ الحَلِفَ بغير الله فَلْيَلْزَمِ الصَّمْتَ فإنَّ هذا أسلَم له. فَضِيلةُ عُمَر-رضي الله عنه- بِسُرْعَةِ امْتِثَالِه وَحُسْنِ فَهْمِهِ وتَوَرُعِه. المبالَغة في الاحْتِيَاطِ وأَنْ لا يَجْرِي على اللسَانِ ما صُورَتُه صورةُ الممنُوعِ شَرْعاً لأنَّ الحاكِي عَنْ غَيْرِه لَيْسَ عَلَيْه شَيءٌ.