Muwatta Imam Malik Book of Divorce, Hadith 108

108 Yahya related to me from Malik that he had heard that the Messenger of Allah ﷺ visited Umm Salama while she was in mourning for Abu Salama and she had put aloes on her eyes. He said, "What is this, Umm Salama?" She said, "It is only aloes, Messenger of Allah." He said, "Put it on at night and wipe it off in the daytime."
Malik said, "The mourning of a young girl who has not yet had a menstrual period takes the same form as the mourning of one who has had a period. She avoids what a mature woman avoids if her husband dies."
Malik said, "A slave-girl mourns her husband when he dies for two months and five nights like her idda.''
Malik said, "An umm walad does not have to mourn when her master dies, and a slave-girl does not have to mourn when her master dies. Mourning is for those with husbands."

وَحَدَّثَنِي عَنْ مَالِكٍ، أَنَّهُ بَلَغَهُ أَنَّ رَسُولَ اللَّهِ ﷺ دَخَلَ عَلَى أُمِّ سَلَمَةَ وَهِيَ حَادٌّ عَلَى أَبِي سَلَمَةَ وَقَدْ جَعَلَتْ عَلَى عَيْنَيْهَا صَبِرًا فَقَالَ " مَا هَذَا يَا أُمَّ سَلَمَةَ " . فَقَالَتْ إِنَّمَا هُوَ صَبِرٌ يَا رَسُولَ اللَّهِ . قَالَ " اجْعَلِيهِ فِي اللَّيْلِ وَامْسَحِيهِ بِالنَّهَارِ " .