Brother Samuel Rolfe, who was seriously afflicted with a felon upon one of his hands, was present [at the dedication of the Nauvoo Temple baptismal font]. President Joseph instructed him to wash in the font and told him that the hand would be healed. The doctors had told him that he could not recover before Spring, and had advised him to have his hand cut. He dipped his hand in the font, and within a week he was perfectly healed.
[Source: Fillerup, Robert C., compiler; William Clayton Nauvoo Diaries and Personal Writings, A chronological compilation of the personal writings of William Clayton while he was a resident of Nauvoo, Illinois. http://www.boap.org/LDS/Early-Saints/clayton-diaries]