Silsilat al-Ahadith al-Sahihah

Sayyiduna Abdullah bin Umar (may Allah be pleased with them) says: I heard the Messenger (peace and blessings of Allah be upon him) say: "Swearing an oath by anyone other than Allah is shirk (associating partners with Allah)."

Lady Qateela bint Safiyyah (may Allah be pleased with her) from the tribe of Juhaina says: A Jewish scholar came to the Prophet (peace and blessings be upon him) and said: You people commit shirk because you say: "Whatever Allah wills and you will," and you swear by the Ka'bah. The Messenger of Allah (peace and blessings be upon him), upon hearing this, said: "You should say: Whatever Allah wills and then you will, and when swearing, say: By the Lord of the Ka'bah."

Sayyiduna Abdullah bin Umar (may Allah be pleased with them) narrates that the Noble Prophet (peace and blessings of Allah be upon him) said: "Swear by Allah, fulfill it, and speak the truth, because Allah dislikes swearing by other than Him."

Sayyidah Qutaylah bint Safi Juhaniyyah (may Allah be pleased with her) says: A Jewish scholar came to the Messenger of Allah (peace and blessings be upon him) and said: O Muhammad! You are the best of people, but if only you did not commit shirk? The Prophet (peace and blessings be upon him) said: “Subhan Allah! (How astonishing!) How is that?” He said: When you swear an oath, you say: By the Ka‘bah. The Prophet (peace and blessings be upon him) remained silent for a while and then said: “This man has spoken the truth. Now, whoever swears an oath should swear by the Lord of the Ka‘bah (and not by the Ka‘bah itself).” He then said: O Muhammad (peace and blessings be upon him)! You are very good people, but if only you did not set up equals with Allah! The Prophet (peace and blessings be upon him) said: Subhan Allah! How is that? He said: You say: Whatever Allah wills and you will. The Messenger of Allah (peace and blessings be upon him) remained silent for a while, then said: “This man has spoken the truth. If anyone says ‘Masha Allah’, he should say «ثُم شئت» (i.e., whatever Allah wills and then you will).”