Musnad Ahmad 304

Yazid narrated to us; ‘Abd al-Malik informed us, from Anas ibn Sirin, who said: I said to Ibn ‘Umar, ‘Tell me about your divorcing your wife.’ He said, ‘I divorced her while she was menstruating.’ I mentioned that to ‘Umar ibn al-Khattab, may Allah be pleased with him, and he mentioned it to the Prophet, peace and blessings be upon him. The Prophet said, ‘Tell him to take her back. When she becomes pure, let him divorce her during her period of purity.’ I asked him, ‘Did you count the divorce you pronounced while she was menstruating?’ He said, ‘Why would I not count it, even though I had acted helplessly and foolishly?’