§ Of the Beginning of Days The Silmarillion

But Ilúvatar knew that Men, being set amid the turmoils of the powers of the world, would stray often, and would not use their gifts in harmony; and he said: ''These too in their time shall find that all that they do redounds at the end only to the glory of my work.' Yet the Elves believe that Men are often a grief to Manwë, who knows most of the mind of Ilúvatar; for it seems to the Elves that Men resemble Melkor most of all the Ainur, although he has ever feared and hated them, even those that served him.