The Messenger of Allah (ﷺ) put on Ihigm for Hajj. When four days of Dhu'l-Hijja were over, he led the dawn prayer, and when the prayer was complete, he said: He who wants to change it to Umra may do so.
Sahih Muslim Book 15, Hadith 218
← Previous Hadith When the backs of their camels would become all right and traces (if the pilgrims) would be effaced (from the paths) and the month of Safar would be over, then Umra would be permissible for one who wants to perform it. When Allah's Apostle (ﷺ) and his Companions came in the state of Ihram for performing Hajj on the fourth (of Dhu'l-Hijja) he (Allah's Apostle) commanded them to change their state of Ihram (from Hajj) to that of 'Umra. It was something inconceivable for them. So they said: Messenger of Allah, is it a complete freedom (of the obligation) of Ihram? Thereupon he said: It is a complete freedom (from Ihram).

Sahih Muslim Book 15, Hadith 217 Next Hadith → We went out with the Messenger of Allah (ﷺ) pronouncing Talbiya for Hajj, And in an the ahadith (narrated in this connection the words are): He led the morning prayer at al-Batha', except al- jahdami who did not make mention of it.

Sahih Muslim Book 15, Hadith 219