Musannaf Ibn Abi Shaybah 9859 — How many days there are in a month

Sayyiduna Jabir (may Allah be pleased with him) said: Once the Prophet (peace and blessings be upon him) swore not to go to his wives for a month, and he went up to an upper room. When twenty-nine days had passed, Jibril came and said: "A month has passed; come down."