Flashback
From ZFGCpedia
During the travel to the desert, Link begins to reminisce on past events in Termina, and remembered the song that the Happy Mask Salesman had taught him, The Song of Healing. Link attempted to use the song on Kafei, however, this did not heal him of his lost memories. The battle he had with the dark figure severed his memories entirely. He still recognized Link from seeing him in Termina, however, the events of which Link helped him out with had been long gone. Skull Kid spoke to Link once again and described the dark figure to Link.