Sayyiduna Abdullah bin Amr (may Allah be pleased with him) narrates: When the Prophet (peace and blessings be upon him) lay down to sleep, he (peace and blessings be upon him) used to recite: 'Bismika rabbi faghfir li dhanbi' (O my Lord, with Your name, seeking its blessing, forgive me my sin).
Ahmad recorded it, and its chain is hasan (good).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الأذكار / 17045