Shubeik Lubeik

The ending doesn't make sense to me. He spends 1/3 of the book in a moral quandary about using the wish, then he randomly uses it for a stupid reason on a donkey? Is he really going to risk his immortal soul for a dumb donkey? It's totally inconsistent with his entire character.

Also the time travel aspect seems like it would create too much inconsistency in the world if wishes actually have that ability.