Musannaf Ibn Abi Shaybah

Ibn Aun narrates: I was with Mujahid in the market of Kufa, where the tents (platforms) of the tailors were set up in front of the houses of Banu al-Bakka, adjacent to the market. He (may Allah have mercy on him) said: Ibn Umar (may Allah be pleased with them both) used to seek permission from them. I asked: How did he do it? He replied: He would say, "Peace be upon you, may I enter?" Then he would enter.