Indeed, Allah Almighty forbids you to swear by your forefathers
Authenticعَنْ عُمَرَ بْنِ الْخَطَّابِ رضي الله عنه قَالَ: قَالَ رَسُولُ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ: «إِنَّ اللهَ عَزَّ وَجَلَّ يَنْهَاكُمْ أَنْ تَحْلِفُوا بِآبَائِكُمْ»، قَالَ عُمَرُ: فَوَاللهِ مَا حَلَفْتُ بِهَا مُنْذُ سَمِعْتُ رَسُولَ اللهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ نَهَى عَنْهَا ذَاكِرًا وَلَا آثِرًا.
‘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 Almighty forbids you to swear by your forefathers." ‘Umar said: By Allah, I have never sworn by that since I heard that the Messenger of Allah (may Allah's peace and blessings be upon him) forbade it, neither deliberately nor reporting it from others.
Explanation
The Prophet (may Allah's peace and blessings be upon him) informed us that Allah Almighty forbids swearing by the forefathers. So, whoever wants to swear should swear by Allah only and none but Him. ‘Umar ibn al-Khattāb, then, mentioned that ever since he heard the Prophet (may Allah's peace and blessings be upon him) prohibit it, he never swore by other than Allah neither intentionally nor by reporting such an oath on behalf of others.
Benefits
- The prohibition of swearing by other than Allah, especially by the forefathers was a habit practiced in the pre-Islamic era of ignorance.
- Swearing means taking an oath by Allah, His Names, or His Attributes regarding some matter as a form of affirmation.
- The superiority of ‘Umar (may Allah be pleased with him), given his quick compliance, good understanding, and prudence.
Source · Agreed upon
From the Hadith Encyclopedia (hadeethenc.com).