Musannaf Ibn Abi Shaybah 27647 — Asking permission to enter: how many

It is narrated from Sayyiduna Abu Sa'id (may Allah be pleased with him) that Sayyiduna Abu Musa al-Ash'ari (may Allah be pleased with him) asked permission from Sayyiduna Umar (may Allah be pleased with him) three times, and he did not give him permission, so he went back. Sayyiduna Umar (may Allah be pleased with him) sent a messenger to summon him and asked: "What made you turn back?" He said: "I asked permission three times, as the Messenger of Allah (peace and blessings be upon him) commanded us: if we are given permission we enter, and if we are not given permission we go back." Sayyiduna Umar (may Allah be pleased with him) said: "Bring some testimony for this, or else I will do such and such (I will punish you)." So he came to a gathering of people and put them under oath about the matter, and they testified in his favor. Then Sayyiduna Umar (may Allah be pleased with him) let him go.