It is narrated from Sayyiduna Abdullah bin Umar (may Allah be pleased with them both) that he instructed a man that when he comes to his bed to sleep, he should recite this supplication: "O Allah! Indeed, You created my soul and You will take it back... O Allah! I ask You for well-being." (O Allah! Surely, You created my soul and You alone will cause it to die; its death and life are for You. If You keep it alive, then protect it, and if You cause it to die, then forgive it. O Allah! I ask You for well-being.)