Musannaf Ibn Abi Shaybah 27331 — Asking permission

Amir bin Abdullah bin al-Zubayr said that Rayhanah narrated: My family sent me to Sayyiduna Umar (may Allah be pleased with him), and I entered upon him without permission. He taught me how to seek permission and said: Go out, then give the salam, and when your salam has been answered, then ask for permission.