Silsilat al-Ahadith al-Sahihah

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."