Volume 1, Book 8, Number 393:
Narrated Jabir:
Allah’s Apostle used to pray (optional, non-obligatory prayer) while riding on his mount (Rahila)
wherever it turned, and whenever he wanted to pray the compulsory prayer he dismounted and
prayed facing the Qibla.
Volume 1 – 105 / 1700
SAHIH BUKHARI VOLUME 1 > BOOK 8: PRAYERS (SALAT)