Musannaf Ibn Abi Shaybah 27330 — Asking permission

Rib'i said that a man of Banu Amir narrated to him that he sought permission from the Prophet (peace and blessings be upon him) while he (peace and blessings be upon him) was in a house. The man said: Shall I come in? The Prophet (peace and blessings be upon him) said to his servant: "Go out to him and teach him how to seek permission. Tell him to say: As-salamu alaykum (peace be upon you), may I enter?" The man heard this and said: As-salamu alaykum, may I enter? So the Prophet (peace and blessings be upon him) gave him permission to enter, and he entered.