At the entrance to the Sacred Grove, you will howl from a symbol on the ground (resembling the Triforce) to make two stone giants come to life on a group of blocks. They will ask you to lead them to their sentry post by hopping on the blocks. Jump in the following pattern: left, down, right, right, up, left, up, up, left, down, down, right, up. They will congratulate you and allow you to pass on to the Master Sword.