`Sayyiduna Umar bin Khattab (may Allah be pleased with him) says that the Messenger of Allah (peace and blessings be upon him) said that Allah Almighty forbids you from swearing by your forefathers. Sayyiduna Umar (may Allah be pleased with him) said: By Allah! Since I heard this from the Messenger of Allah (peace and blessings be upon him), I have not sworn by (my forefathers), neither on my own behalf nor while quoting someone else.