Sahih Muslim
The Book Pertaining to the Remembrance of Allah, Supplication, Repentance and Seeking Forgiveness (Kitab Al-Dhikr)
Book Number: 035 / Hadith Number: 6574
This hadith has been narrated on the authority of 'Asim b. Kulaib with the same chain of transmitters that Allah's Messenger (may peace be upon him) said to me: Say:" O Allah, I beg of Thee righteousness and adhering to the straight path."