In chapter 7 of The Silmarillion, "Of the Silmarils", it is stated that the jewels could harm men or those with evil intent:
And Varda hallowed the Silmarils, so that thereafter no mortal flesh, nor hands unclean, nor anything that was evil will might touch them, but it was scorched and withered;
However, Beren, in his capture of one Silmaril (chapter 19, "Of Beren and Luthien"), is somehow exempt from this:
As he closed it in his hand, the radiance welled through his living flesh, and his hand became as a shining lamp; but the jewel suffered his touch and hurt him not.
Beren is certainly not evil but is definitely a man. Why should he be exempt (other than it helping the narrative), and more interestingly, who could have power over the Silmaril in such a way? Could Varda revoke her blessings or was this some kind of intervention from Eru? Or is this line papering over an earlier version of the story when Tolkien considered Beren to be an elf?