This paper discusses Richard Moran’s account of testimony. Moran argues for the idea that a person who testifies should be considered as giving assurance rather than providing evidence for her assertion. For Moran, it is the fact that the speaker stands by her assertion P that should be the hearer’s reason for believing P. I argue that, even if this claim is true, the speaker’s assurance should be considered as weak and untenable by itself. I draw my argument from the (...) role of sincerity in testimony. Moran views sincerity as giving access to what the speaker assumes responsibility for, but I contend that the view is too optimistic. Sincerity does not guarantee access to the speaker’s commitment to her own words, and for this reason, it is unclear whether the assurance from sincere testimony is a good reason for belief. (shrink)