Narrated Al-Bara bin `Azib:
Allah's Messenger (ﷺ) said to me, "When you want to go to bed, perform ablution as you do for prayer, then lie down on your right side and say: 'Allahumma aslamtu wajhi ilaika, wa fauwadtu `Amri ilaika wa aljatu zahri ilaika, raghbatan wa rahbatan ilaika, lamalja'a wa la manna mink a ill a ilaika. Amantu bikitabi kalladhi anzalta wa bi nabiyyikal-ladhi arsalta'. If you should die then (after reciting this) you will die on the religion of Islam (i.e., as a Muslim); so let these words be the last you say (before going to bed)" While I was memorizing it, I said, "Wa birasiulikal-ladhi arsalta (in Your Apostle whom You have sent).' The Prophet (ﷺ) said, "No, but say: Wa binabiyyi-kalladhi arsalta (in Your Prophet whom You have sent).