Musannaf Ibn Abi Shayba 27:445

Affan narrated to us, he said: Hammad bin Salamah narrated to us, he said: Muhammad bin Ishaq narrated to us, from Muhammad bin Ibrahim, from Salamah bin Abi al-Tufayl, from Ali bin Abi Talib, that the Prophet, peace and blessings of Allah be upon him, said to him: "O Ali, indeed you have a treasure in Paradise, and you are the possessor of its two horns. So do not follow a glance with a glance, for indeed you have the first [glance], and you do not have the second."