The Prophet said to him, "Then fast and break your fast, pray and sleep, and fast one day out of every ten, and you will have the reward of the other nine."
قال له النبي: فصم أو أفطر، وصل ونم، وصم من كل عشرة أيام يوما، ولك أجر تسعة.
Bukhari narrated it in the Book of Fasting (1977), and Muslim in the Book of Fasting (1159:186), both from the hadith of Ibn Jurayj, who said, I heard Ataa claim that Abu Abbas the poet informed him that he heard Abdullah bin Amr bin As, and then he mentioned it. The wording is that of Muslim, and Bukhari did not mention this wording in the place referred to.