Musnad Ahmad 32:963

Waki’ narrated to us, from Sufyan, from al-Qasim ibn Shurayh, from Abu Bahr, from Anas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "I am amazed at the believer; indeed, Allah does not decree a decree for the believer except that it is good for him." (Abu Bahr’s name is Tha’labah).