From Sahih Muslim (Hadith 2988):
Hafsa (Allah be pleased with her) said that Allah's Apostle (ﷺ) commanded his wives that they should put off Ihram during the year of Hajj (at-ul-Wada'). whereupon she (Hafsa) said:What hinders you that you have not put off Ihram? Thereupon he said: I have stuck my hair and driven my sacrificial animal along with men and it is not permissible to put off Ihram (under this condition until I have sacrificed the animal)
Reference: Muslim 2988