The Silmarillion

Great was the anger of Ar-Pharazôn at these tidings, and as he pondered long in secret, his heart was filled with the desire of power unbounded and the sole dominion of his will. And he determined without counsel of the Valar, or the aid of any wisdom but his own, that the title of King of Men he would himself claim, and would compel Sauron to become his vassal and his servant; for in his pride he deemed that no king should ever arise so mighty as to vie with the Heir of Eärendil. Therefore he began in that time to smithy great hoard of weapons, and many ships of war he built and stored them with his arms; and when all was made ready he himself set sail with his host into the East.

And men saw his sails coming up out of the sunset, dyed as with scarlet and gleaming with red and gold, and fear fell upon the dwellers by the coasts, and they fled far away. But the fleet came at last to that place that was called Umbar, where was the mighty haven of the Númenóreans that no hand had wrought. Empty and silent were all the lands about when the King of the Sea marched upon Middle-earth. For seven days he journeyed with banner and trumpet, and he came to a hill, and he went up, and he set there his pavilion and his throne; and he sat him down in the midst of the land, and the tents of his host were ranged all about him, blue, golden, and white, as a field of tall flowers. Then he sent forth heralds, and he commanded Sauron to come before him and swear to him fealty.

And Sauron came. Even from his mighty tower of Barad-dûr he came, and made no offer of battle. For he perceived that the power and majesty of the Kings of the Sea surpassed all rumour of them, so that he could not trust even the greatest of his servants to withstand them; and he saw not his time yet to work his will with the Dúnedain. And he was crafty, well skilled to gain what he would by subtlety when force might not avail. Therefore he humbled himself before Ar-Pharazôn and smoothed his tongue; and men wondered, for all that he said seemed fair and wise.

But Ar-Pharazôn was not yet deceived, and it came into his mind that, for the better keeping of Sauron and of his oaths of fealty, he should be brought to Númenor, there to dwell as a hostage for himself and all his servants in Middle-earth. To this Sauron assented as one constrained, yet in his secret thought he received it gladly, for it chimed indeed with his desire. And Sauron passed over the sea and looked upon the land of Númenor, and on the city of Armenelos in the days of its glory, and he was astounded; but his heart within was filled the more with envy and hate.

Yet such was the cunning of his mind and mouth, and the strength of his hidden will, that ere three years had passed he had become closest to the secret counsels of the King; for flattery sweet as honey was ever on his tongue, and knowledge he had of many things yet unrevealed to Men. And seeing the favour that he had of their lord all the councillors began to fawn upon him, save one alone, Amandil lord of Andúnië. Then slowly a change came over the land, and the hearts of the Elf-friends were sorely troubled, and many fell away out of fear; and although those that remained still called themselves the Faithful, their enemies named them rebels. For now, having the ears of men, Sauron with many arguments gainsaid all that the Valar had taught; and he bade men think that in the world, in the east and even hi the west, there lay yet many seas and many lands for their winning, wherein was wealth uncounted. And still, if they should at the last come to the end of those lands and seas, beyond all lay the Ancient Darkness. 'And out of it the world was made. For Darkness alone is worshipful, and the Lord thereof may yet make other worlds to be gifts to those that serve him, so that the increase of their power shall find no end.'

And Ar-Pharazôn said: 'Who is the Lord of the Darkness?'

Then behind locked doors Sauron spoke to the King, and he lied, saying: 'It is he whose name is not now spoken; for the Valar have deceived you concerning him, putting forward the name of Eru, a phantom devised in the folly of their hearts, seeking to enchain Men in servitude to themselves. For they are the oracle of this Eru, which speaks only what they will. But he that is their master shall yet prevail, and he will deliver you from this phantom; and his name is Melkor, Lord of All, Giver of Freedom, and he shall make you stronger than they.'