Volume 7, Book 62, Number 131:
Narrated Ibn ‘Abbas:
One morning we saw the wives of the Prophet weeping, and everyone of them had her family
with her, I went to the mosque and found that it was crowded with people. Then ‘Umar bin Al-Khat –
tab came and went up to the Prophet who was in his upper room. He greeted him but nobody
answered. He greeted again, but nobody answered. Then the gatekeeper called him and he entered
upon the Prophet, and asked, “Have you divorced your wives?” The Prophet, said, “No, but I have
taken an oath not to go to them for one month.” So the Prophet stayed away (from his wives) for
twenty nine days and then entered upon them.