Hazrat Rabi'i narrates that a person from Banu Amir told me that he sought permission from the Prophet Muhammad (peace and blessings be upon him) while the Prophet (peace and blessings be upon him) was in the house. That person said: "May I come in?" The Prophet (peace and blessings be upon him) said to his servant: "Go to him and teach him the manner of seeking permission. Tell him to say: 'Assalamu Alaikum, may I come in?'" The man heard this and said: "Assalamu Alaikum, may I come in?" So the Prophet (peace and blessings be upon him) granted him permission to enter, and he entered.