The Messenger of Allah (PBUH) combined Hajj and 'Umrah, then he died and he neither had forbidden it nor Qur’an had been revealed forbidding it.

We set out with the Messenger of Allah (PBUH) five days before the end of Zthul-Qi'dah intending to observe Hajj. When we approached Mecca, the Messenger of Allah (PBUH) commanded that whoever did not have a sacrificial animal with him, should exit state of ihram after circumambulating the House [Ka'bah] and pacing between Safa and Marwah. 'A'ishah said: Then on the Slaughter [Sacrifice] day, Beef was brought to us. I said: What is this? They said: The Messenger of Allah (PBUH) has slaughtered [sacrificed] on behalf of his wives.

'Ali came from Yemen, and the Prophet (PBUH) said to him: Which form of Hajj [Ifrad, Tamattu', Qiran] did you intend with your talbiyah and ihram? He said: I intended what the Prophet of Allah (PBUH) intended. He said: If I had not had the sacrificial animal with me, I would have exited state of Ihram [after performing 'Umrah].

Ibn 'Umar wanted to perform Hajj in the year when Al-Hajjaj attacked Ibn Al-Zubeiyr, and he was told that people were fighting each other, and we fear that they could prevent you. He recited: (Verily, in the Messenger of Allah you have an excellent example) [Al-Ahzab: 21]. So, I will do as the Messenger of Allah (PBUH) did. Bear witness that I have resolved to perform 'Umrah. Then he set out until he was in the desert. Then he said. I believe that they are both the same. I bear witness that I have resolved to perform Hajj along my 'Umrah. Then he bought a sacrificial animal from Qudeid and set out reciting talbiyah for boyth [Hajj and 'Umrah] until he reached Mecca. He then circumambulated the House [Ka'bah], and paced between As-Safa and Al-Marwah, and did not do more than that. He neither sacrificed, nor shaved or cut his hair, and did not make anything lawful which was forbidden [due to ihram], until the Day of Sacrifice. So he sacrificed and shaved. He considered that he had completed the circumambulation of Hajj and Umrah with his first circumambulation, and said: This is what the Messenger of Allah (PBUH) did.

The Messenger of Allah (PBUH) entered state of ihram for a Hajj only (Ifrad).