Sahih Muslim Book 7, Hadith Number 2790.

Chapter : Types of Ihram- It is permissible to enter into the state of Ihram singularly for the sake of Hajj or for tamattu’ bi’l-‘umra ila’l-Hajj or for both hajj and ‘umra together.

Abd al-Rahman b. Abu Bakr reported that the Apostle of Allah (may peace be upon him) ordered him to mount ‘Aisha behind him and enable her to (enter into the state of Ihram for ‘Umra) at Tan’im.