Sayyiduna Shaddad bin Aws (may Allah be pleased with him) narrated: Shall I not teach you what the Prophet (peace and blessings be upon him) used to teach us? "O Allah, I ask You for steadfastness in the matter (of religion) and firm resolve upon right guidance; I ask You for gratitude for Your blessing and excellence in Your worship; I ask You for a sound heart and a truthful tongue; I ask You for the good that You know, I seek refuge in You from the evil that You know, and I seek Your forgiveness for what You know." And the Prophet (peace and blessings be upon him) said: "There is no Muslim servant who recites a surah from the Book of Allah at the time of his sleep, except that Allah appoints an angel over him, and then nothing comes near him (that servant) until he wakes, whenever he wakes."
Hadith Referenceالمعجم الكبير للطبراني / باب الشين / 7144