This particular neighbor had a bad temper, and Nasruddin was reluctant to refuse him.
"Let me go ask the donkey," he said.
A few moments later, Nasruddin returned.
"My deepest apologies," he said to his neighbor, "but the donkey refuses. He explained his reasoning like this: if I make him work for you, you are likely to beat him, and if you beat him, he will bite you, and after he bites you, you will curse me. So really, it's better for all of us if I do not loan you the donkey."
Inspired by: The Wit and Wisdom of Nasraddin Hodja by Nejat Muallimoglu
Notes: This story is on p. 121 of the book. In other versions of this story, Nasruddin comes back and tells the neighbor that the donkey refuses, whereupon the neighbor loses his temper and starts screaming and shouting, whereupon Nasruddin says, "That's just what the donkey was talking about."