I had in fact no need of it, but I heard Allah's Messenger (ﷺ) as saying: It is not permissible for the women believing in Allah and the Hereafter to abstain from adornment beyond three days except (at the death of) husband (in which case she must abstain from adornment) for four months and ten days.
Sahih Muslim Book 18, Hadith 79
← Previous Hadith Umm Salama and Umm Habiba (Allah be pleased with them) were talking with each other (and saying) that a woman came to Allah's Messenger (ﷺ) and mentioned to him that her daughter had lost her husband, and her eyes were sore and she wanted to use collyrium, whereupon Allah's Messenger (ﷺ) said: One among you used to throw dung at the end of a year, and now (this abstinence from adornment) is only for four months and ten days.

Sahih Muslim Book 18, Hadith 78 Next Hadith → It is not permissible for a woman believing in Allah and the Hereafter (or believing in Allah and His Messenger) that she should observe mourning for the dead beyond three days except in case of her husband.

Sahih Muslim Book 18, Hadith 80