Musannaf Ibn Abi Shayba 17:1225

Abu Mu'awiyah narrated to us, from al-A'mash, from Habib, from 'Abdullah ibn Babah, from Abu Hurayrah, who said: "Whoever says when he goes to his bed: 'There is no god but Allah alone, He has no partner, to Him belongs the dominion, and to Him belongs the praise, and He is capable of all things. Glory be to Allah and by His praise, there is no god but Allah, Allah is the Greatest,' his sins will be forgiven, even if they were like the foam of the sea."