Sahih Muslim Book 7, Hadith Number 2835.

Chapter : The Qarin should not put off the Ihram but at the time when a Mufrid pilgrim takes it off.

Hafsa (Allah be pleased with her) reported: I said to Allah’s Messenger (may peace be upon him): What is the matter with people that they have put off Ihram, whereas you have not put it off after your Umra’? He said: I have driven my sacrificial animal and stuck my hair, and it is not permissible for me to put off Ihram unless I have completed the Hajj.