Sahih Muslim
The Book Pertaining to the Remembrance of Allah, Supplication, Repentance and Seeking Forgiveness (Kitab Al-Dhikr)
Book Number: 035 / Hadith Number: 6545
This hadith has been transmitted on the authority of al-Bara' b. 'Azib with a slight variation of wording and there is this addition in the hadith transmitted on the authority of Husain:" In case you get up in the morning, you will get up with bliss."