It is narrated from Sayyiduna Abu Zuhayr al-Anmari (may Allah be pleased with him) that when the Prophet (peace and blessings be upon him) lay down on his bed, he would say: "Allahummaghfir li dhanbi, wa akhzi al-shaytan, wa fukka rihani, wa thaqqil mizani, waj'alni fi al-nadiyy al-a'la (O Allah, forgive me my sin, disgrace Satan, free my pledged soul, make my scale heavy, and place me in the highest assembly)."
Hadith Referenceالمعجم الكبير للطبراني / مسند من يعرف بالكنى / 18962