(4) باب جَوَازِ صَلاَةِ النَّافِلَةِ عَلَى الدَّابَّةِ فِي السَّفَرِ حَيْثُ تَوَجَّهَتْ
This hadith has been narrated by another chain of transmitters and in the one narrated by Ibn Mubarak and Ibn Abu Za'ida (these words are narrated). Ibn 'Umar then recited:
" Whether you turn thither is Allah's face," and it was revealed in this context.
Reference: Sahih Muslim 700 d
In-book reference: Book 6, Hadith 44
USC-MSA web (English) reference(deprecated numbering scheme): Book 4, Hadith 1500