Sahih Muslim Book 7, Hadith Number 2782.

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.

Ibn al-Muththanna reported on the authority of Ibn Abu’Adi who transmitted on the authority of Ibn’Aun who narrated from al-Qasim and Ibrahim having said: I cannot differentiate the Hadith of one from the other (Qasim and Ibrahim) that the Mother of the Believers (Allah be pleased with her) said this: Messenger of Allah, people have come back with two acts of worship. The rest of the Hadith is the same.