[Inziladun]

As soon as he was confronted by Eru, Aulë realized (or allowed himself to be released from self-delusion) that he had committed a serious error.
The Valar had not been authorized by Eru to attempt new "creations" of their own, but merely to oversee what the Creator had established. Aulë considered that his only recourse was to express his true humility and sense of guilt by wiping out the physical traces of his act. As Aulë had made them, destroying them would not have actually been "killing", since Aulë as a creation himself had not been able to imbue them with a sense of being. It was only Eru, seeing the humility and heartfelt sorrow of Aulë, who was able to give the Dwarves true life. He did so out of pity for Aulë and an understanding of Aulë's motives, which had not been evil.