Answer:
What do you fill with empty hands?
A precious stone, as clear as diamond. Seek it out while the sun's near the horizon. Though you can walk on water with its power, try to keep it, and it'll vanish in an hour.
What tastes better than it smells?
What is it that has four legs, one head, and a foot?
I dig out tiny caves and store gold and silver in them. I also build bridges of silver and make crowns of gold. They are the smallest you could imagine. Sooner or later everybody needs my help. Yet many people are afraid to let me help them.
Do what he says and you'll be fine, don't and you lose the game.