Musannaf Ibn Abi Shayba 33:270

Abdullah ibn Idris narrated to us, from Isma'il and Sufyan, from Zubayd ibn al-Harith, from a man from Banu 'Amir, who said: Ali said: "I only fear two things for you: long hopes and following desires. For long hopes make one forget the Hereafter, and following desires divert one from the truth. Indeed, the world has departed, turning its back, and the Hereafter is approaching. Each of them has sons, so be sons of the Hereafter. For today is action without reckoning, and tomorrow is reckoning without action."