It is narrated from Sayyidah Asma' bint Umays (may Allah be pleased with her) that the Prophet (peace and blessings be upon him) said to her: "O daughter of Umays! Ghusl, Jumu'ah, shaving the head and cutting the hair are not obligatory upon you women, except that when one of you performs Hajj, on the Day of Sacrifice she herself, or one of her mahram relatives, should take a little from the ends of the hair at the front of her head."
Hadith Referenceالمعجم الكبير للطبراني / مسند النساء / 20738