It is narrated from Sayyidah Umm Salamah (may Allah be pleased with her) that a woman whose husband had died had a complaint in her eye, so those people came to the Prophet (peace and blessings be upon him) and asked his permission for kohl, and mentioned that they feared for her eye. So the Prophet (peace and blessings be upon him) said: "Previously one of you would stay in her house for a year, then when the year was complete she would throw a piece of dung. So can she not (wait) even four months and ten days?"
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20115