What did the Prophet Muhammad (saw) tell Ibn `Umar regarding swearing by his fathers?
 Narrated Ibn `Umar:                     I heard `Umar saying, "Allah's Apostle said to me, 'Allah forbids you to swear by your fathers." `Umar said, "By Allah! Since I heard that from the Prophet , I have not taken such an oath, neither intentionally, nor by reporting the oath of someone else."