Musnad Ahmad 26:537

Yahya ibn Sa’id narrated to us, from Sufyan, Mansur and Sulayman narrated to me, from Ibrahim, from ‘Ubaydah, from ‘Abdullah: That a Jew came to the Prophet, may Allah bless him and grant him peace, and said: "O Muhammad, indeed Allah holds the heavens upon a finger, and the earths upon a finger, and the mountains upon a finger, and the creatures upon a finger, and the trees upon a finger, then He says: 'I am the King.'" The Messenger of Allah, may Allah bless him and grant him peace, laughed until his molars appeared, and he said: "And they have not appraised Allah with true appraisal" [Al-An'am: 91]. Yahya said: And Fudayl—meaning Ibn ‘Iyad—said: "In astonishment and confirmation of him."