Is prayer valid on the back of a moving animal?

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Prayer is valid on the back of an animal if the worshipper can fulfill all the pillars (arkān) of the prayer upon it, and this applies particularly to optional prayers (nafilah) during travel. If the animal itself is impure, or if the worshipper places a pure mat upon it, the prayer remains valid. This is supported by the action of the Prophet (peace be upon him) praying on a donkey, which Anas also did.