The Galak centaur in the Thousand Needles are protecting an artifact from the time of the centaurs' creation.
We would like to retrieve it, but we require a phial of water from one of the night elves' moonwells.
To collect the water, you will first need to obtain one of the phials carried by the dryads near the Raynewood Retreat in the heart of Ashenvale Forest. There is a moonwell near the western bank of the Falfarren River, south of the main road, where you can fill the phial.
Very good. This should fill Rau's request just fine. Could you deliver this to him? You might enjoy spending some time out in the Needles.