Musnad Abu Ya'la al-Mawsili 219:2

Abu Khaythama narrated to us, Jarir narrated to us, from Yahya, from Humayd ibn Nafi’, from Zaynab bint Abi Salamah, from her mother, Umm Salamah, and Umm Habibah, the two wives of the Prophet (may Allah bless him and grant him peace), who both said: A woman came to the Prophet (may Allah bless him and grant him peace) and said: "O Prophet of Allah, my daughter’s husband has died, and she is in her waiting period (iddah), and I fear for her eye, so may I apply kohl to it?" The Messenger of Allah (may Allah bless him and grant him peace) said: "A woman among you used to throw a piece of dung at the end of a year, and it is only four months and ten [days]."