Musnad Ahmad 25:387

Isma'il ibn Yazid al-Raqqi Abu Yazid narrated to us, Furat narrated to us, from 'Abd al-Karim, from 'Ikrimah, from Ibn 'Abbas, who said: Abu Jahl said: "If I see the Messenger of Allah praying at the Ka'bah, I will certainly come to him until I step on his neck." He (Ibn 'Abbas) said: He (the Prophet) said: "If he had done so, the angels would have seized him openly. And if the Jews had wished for death, they would have died and seen their places in the Fire. And if those who engaged in *mubahalah* (mutual imprecation) with the Messenger of Allah, peace and blessings of Allah be upon him, had gone out, they would have returned finding neither wealth nor family."