A'isha (Allah be pleased with her) said: Some among us put on Ihram for Hajj alone (Hajj Mufrad); some of us for Hajj and 'Umrah together (Qiran), and some of us for Tamattau (first for 'Umrah and after completing it for Hajj).
Hadith ReferenceSahih Muslim / The Book of Pilgrimage / Hadith: 1211