Musannaf Ibn Abi Shayba 33:206

Muhammad ibn Fudayl narrated to us, from Abd al-Rahman ibn Ishaq, from Abd Allah al-Qurashi, from Abd Allah ibn Ukaym, who said: Abu Bakr addressed us and said: "To proceed: I advise you to fear Allah, and to praise Him with that which He is worthy of, and to mix desire with fear, and to combine persistence in supplication. For Allah praised Zakariya and his household, saying: 'Indeed, they used to hasten to good deeds and supplicate to Us in hope and fear, and they were humble to Us.' Then know, O servants of Allah, that Allah has taken your souls as collateral for His right, and has taken your covenants upon that, and has purchased from you the little that is perishable for the much that is everlasting. This is the Book of Allah among you; its wonders do not perish, and its light is not extinguished. So believe His speech, take counsel from His Book, and seek insight in it for the day of darkness. For He only created you for worship, and has appointed over you noble scribes who know what you do. Then know, O servants of Allah, that you go out and return in a term whose knowledge has been hidden from you. If you are able to have your terms expire while you are in the work of Allah, then do so; and you will not be able to do that except by Allah. So race during the respite of your terms before your terms expire, lest they return you to your worst deeds. For there are people who made their terms for others and forgot themselves, so I forbid you from being like them. Haste, haste! Deliverance, deliverance! For behind you is a persistent pursuer—meaning, swift."