Sunan Abi Dawud 3249
سنن أبي داود#3249SahihNarrated Ibn 'Umar:The Messenger of Allah (ﷺ) found 'Umar al-Khattab in a caravan while he was swearing by his father. So he said: Allah forbids you to swear by forefathers. If anyone swears, he must swear by Allah or keep silence
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Al-AlbaniSahih
Muhammad Muhyi Al-Din Abdul HamidSahih
Zubair Ali ZaiSahih Bukhari (6108) Sahih Muslim (1646)
In-book reference: 22:8