Ibn Majah

Benefits and Issues:
Abdullah ibn Umar radi Allahu anhu made a mistake in this matter, which is why he did not state this with certainty.
The aforementioned question was asked by Urwah rahimahullah himself, while both Urwah and Ibn Umar radi Allahu anhu were present near the chamber of Aishah radi Allahu anha, and the Mother of the Believers heard their question and answer.
Upon this, Urwah rahimahullah sought confirmation from the Mother of the Believers radi Allahu anha, so she gave the aforementioned answer from inside the chamber.
Ibn Umar radi Allahu anhu, upon hearing this statement of the Mother of the Believers, remained silent—he neither denied nor affirmed it. (Sahih Muslim, Book of Hajj, Chapter: Clarification of the Number of the Prophet’s ﷺ Umrahs and Their Times, Hadith: 1253)

Hadith Commentary: Benefits and Issues: People were collectively performing the Duha prayer (Salat al-Duha) in the mosque. This specific situation, that people gather in the mosque to perform the Duha prayer together, was declared an innovation (bid‘ah) by Ibn ‘Umar (radi Allahu anhu). From this, it is understood that the noble Companions (radi Allahu anhum ajma‘in) would also consider it an innovation (bid‘ah) to establish a specific form for an act of worship from their own side. In other words, this was not an original or intrinsic innovation (bid‘ah asliyyah wa dhatiyyah), but rather a descriptive innovation (bid‘ah wasfiyyah), which, in its essence and origin, is established, but a specific manner and quality is devised from one’s own side. Otherwise, the Duha prayer itself is established from the practice of the Prophet (sallallahu alayhi wa sallam), as has already been discussed in the section on the Duha prayer.

Hadith Commentary: Benefits and Issues: The Prophet sallallahu alayhi wa sallam performed four ‘umrahs:

➊ The first ‘umrah was in the 6th year of Hijrah, in the month of Dhu al-Qa‘dah, during the year of the Treaty of Hudaybiyyah, which, in terms of reward and merit, was performed, but in practice, the Prophet sallallahu alayhi wa sallam, along with his companions, was prevented from completing it.

➋ The second ‘umrah was in the following year, the 7th year of Hijrah, also in Dhu al-Qa‘dah, which was performed as a make-up (‘umrat al-qada’) as a result of the (peace) treaty. Therefore, it is called ‘umrat al-qada’.

➌ The third ‘umrah was performed in the 8th year of Hijrah, after the conquest of Makkah, from Ji‘ranah.

➍ The ihram (state of consecration) for the fourth ‘umrah was combined with Hajj in Dhu al-Qa‘dah, although it was performed in Dhu al-Hijjah.

And in all of these, Ibn ‘Umar radi Allahu anhu participated, but he considered one of the ‘umrahs to have been in Rajab. From this, it is understood that sometimes a person participates in an event but forgets the exact month or year of its occurrence; therefore, Ibn ‘Umar radi Allahu anhu chose to remain silent.