Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) narrates that indeed the Prophet Muhammad (peace and blessings be upon him) heard Umar (may Allah be pleased with him) saying: "By your father!" So the Prophet (peace and blessings be upon him) said: "Indeed, Allah forbids you from swearing by your fathers." Umar (may Allah be pleased with him) said: "By Allah! After that, I never swore by them, neither intentionally nor quoting someone."