"You got a bottle of Gold Dust! This is the finest quality available! "
Link acquires the valuable Gold Dust after completing the Goron race in first place in the Goron Racetrack. He can give it to Zubora and Gabora, who can use it to reforge his sword into the remarkable Razor Sword, which does twice as much damage as Link's original sword, but can only be used 100 times, after which it will break. It can later be reforged yet again to the Gilded Sword, which is the same as the Razor Sword, but never breaks if Link hands over the Gold Dust again. The Gilded Sword will then be done and acquired on the next day.
Gold Dust can also be sold should Link have no other use for it. He can take it to Zubora and Gabora for a measly 20 Rupees, or he can head over to the Curiosity Shop to sell it for a whopping 200 Rupees.