Narrated Aisha (may Allah be pleased with her): The Prophet (peace and blessings of Allah be upon him) spent a night awake (in vigilance). After arriving in Madinah, he (peace be upon him) said, "Would that a righteous man from among my companions would guard me tonight!" (While these words were being spoken,) we heard the clanging of weapons. The Prophet (peace be upon him) asked, "Who is it?" (The person coming) said, "It is Sa'd bin Abi Waqqas. I have come to guard you." Then the Prophet (peace be upon him) was pleased, prayed for him, and went to sleep.