Mukhtasar Bukhari (Abridged) 1883 — It is forbidden for a mourning

Narrated from Umm al-Mu'mineen Umm Salamah (may Allah be pleased with her): A woman's husband passed away and her eyes started hurting, so people came to the Messenger of Allah (peace and blessings be upon him) to seek permission for her to use kohl. The Prophet (peace and blessings be upon him) said: "She cannot use kohl, even though previously (in the days of ignorance) a woman would complete her waiting period in bad clothes and a bad house, and when a year was completed (she would come out of her waiting period in such a way that) a dog would pass by and she would throw dung at it. Kohl is absolutely not permissible until four months and ten days have passed."