question #3 Sahih al-Bukhari 6108, Book 78, Hadith 135 : What are the consequences of swearing by one’s ancestors in Islam?

that he found `Umar bin Al-Khattab in a group of people and he was swearing by his father. So
Allah’s Messenger (ﷺ) called them, saying, “Verily! Allah forbids you to swear by your fathers. If one has to
take an oath, he should swear by Allah or otherwise keep quiet.”