Musannaf Ibn Abi Shaybah 27333 — Asking permission

Zayd bin Aslam said: My father sent me to Sayyiduna Ibn Umar (may Allah be pleased with them both), and I said to him: Shall I come in? He said: Do not say it like this; rather say: As-salamu alaykum (peace be upon you). When you are told: Wa alaykum as-salam (and upon you be peace), then enter.