Outside the town boundary, voluntary prayer may be performed while mounted:
• Ruku and Sujud are performed by head gestures.
• The Sujud gesture is lower than the Ruku gesture.
• The prayer follows the direction in which the animal naturally travels; facing the Qiblah is not required for this mounted voluntary concession.
• The rule applies even to regular voluntary Sunnahs, although a report from Abu Hanifah gives special emphasis to dismounting for the Fajr Sunnah.
This is a travel-style voluntary concession, not the normal rule for Fard prayer.