§ Of the Rings of Power and the Third Age The Silmarillion

Now all these things were achieved for the most part by the counsel and vigilance of Mithrandir, and in the last few days he was revealed as a lord of great reverence, and clad in white he rode into battle; but not until the time came for him to depart was it known that he had long guarded the Red Ring of Fire. At the first that Ring had been entrusted to Círdan, Lord of the Havens; but he had surrendered it to Mithrandir, for he knew whence he came and whither at last he would return.