Sunan an-Nasa'i 743
سنن النسائي#743SahihIt was narrated that Ibn Umar said:"The messenger of Allah (peace be upon him) used to pray atop his mount while travelling, facing whatever direction it was facing." (One of the narrators) Malik said: "Abdullah bin Dinar said: and Ibn Umar used to do likewise
Scholarly Authentication
We show the most cautious grade (weakest-wins) as the overall label. Individual scholars graded it as follows:
Abu GhuddahSahih
Al-AlbaniSahih
Zubair Ali ZaiSahih
In-book reference: 9:2