Sahih Muslim 1616
صحيح مسلم#1616Sahihوَحَدَّثَنَا يَحْيَى بْنُ يَحْيَى، قَالَ قَرَأْتُ عَلَى مَالِكٍ عَنْ عَبْدِ اللَّهِ بْنِ دِينَارٍ، عَنِ ابْنِ عُمَرَ، أَنَّهُ قَالَ كَانَ رَسُولُ اللَّهِ صلى الله عليه وسلم يُصَلِّي عَلَى رَاحِلَتِهِ حَيْثُمَا تَوَجَّهَتْ بِهِ . قَالَ عَبْدُ اللَّهِ بْنُ دِينَارٍ كَانَ ابْنُ عُمَرَ يَفْعَلُ ذَلِكَ .
Abdullah b. Dinar reported on the authority of Ibn 'Umar that the Messenger of Allah (ﷺ) used to observe prayer on his ride (no matter) in which direction it had its face turned. 'Abdullah b. Dinar said that Ibn 'Umar used to do like that
Scholarly Authentication
The label above is the grade most of these scholars gave — one dissenting opinion no longer speaks for all of them. If any scholar calls a narration fabricated, that verdict is shown instead, whatever the others say. Each scholar's own wording:
Every narration in Sahih Muslim is accepted as Sahih (authentic) by the established status of the book.
In-book reference: 6:47