because some of them were performing the single Hajj (ifrād), others were combining Hajj and ʿUmrah (qirān), and—as one who was himself performing ifrād—he made no mention of the pilgrims who were doing tamattuʿ, even though a number of them belonged to that category. The Prophet ﷺ therefore instructed everyone who had not brought a sacrificial animal to dissolve his Hajj into an ʿUmrah and remain in that state of tamattuʿ until the time for Hajj.
This ḥadīth is one of the proofs cited by those who argue that Hajj must be dissolved into ʿUmrah in such circumstances.

Third ḥadīth
ʿAbd Allāh ibn ʿAbbās reported: “The Messenger of Allah ﷺ and his Companions arrived (in Mecca) on the morning of the fourth of Dhū al-Ḥijjah, raising the talbiyah for Hajj. He ordered them to turn it into an ʿUmrah. They asked, ‘Messenger of Allah, what sort of release do you mean?’ He said, ‘Complete release—every bit of it.’”

Overall meaning:
Ibn ʿAbbās explains that during the Farewell Pilgrimage the Prophet ﷺ and his Companions entered Mecca on the morning of the fourth of Dhū al-Ḥijjah. Some of them were in iḥrām for Hajj alone, while others were combining Hajj and ʿUmrah. The Prophet instructed everyone in those two groups who had not driven a sacrificial animal to come out of their Hajj and regard their consecration as an ʿUmrah instead. This struck them as momentous: to undergo a full release—one that even permitted marital relations—and then enter iḥrām again for Hajj. Hence they asked, “Messenger of Allah, what kind of release?” He replied, “Complete release—every single aspect of it,” meaning that everything prohibited by iḥrām now becomes lawful. They obeyed, may Allah be pleased with them. This report, too, is among the evidences cited by those who hold that such dissolution is obligatory.

Fourth ḥadīth
ʿUrwah ibn al-Zubayr said: “I was sitting when Usāmah ibn Zayd was asked, ‘How did the Messenger of Allah ﷺ ride when he departed (from ʿArafah)?’ He answered, ‘He went at an ʿanq— a steady, relaxed pace— and whenever he found an open space he would move at a nasṣ (a quicker gait).’

Lexical notes:
ʿanq and nasṣ: ʿanq (with an open ʿayn and nūn) and nasṣ (with an open nūn and a doubled ṣād) are two riding gaits, the latter being the faster.

fajwah: with an open fāʾ, denotes a spacious, open area.