While Sauron, who took on a fair guise to deceive the Elves, and the High Elf Cerebrimbor worked together to create the Great Rings, the Elf never fully trusted him. So unknown to Sauron, Celebrimbor created the Three Elven Rings and then hid them from him. Since Sauron never touched the Three Rings or took part in their making, he could never influence or corrupt them.