Sahih Muslim | Book 35 | Chapter 9
Narrated by Qatada
Qatada asked Anas which Supplication Allah's Apostle (may peace be upon him) frequently made. He said: The supplication that he (the Holy Prophet made very frequently is this: "O Allah, grant us the good in this world and the good in the Hereafter and save us from the torment of Hell-Fire." He (Qatada) said that whenever Anas had to supplicate he made this very supplication, and whenever he (intended) to make another supplication he (inserted) this very supplication in that.