Revolvers don't have a safety.
While there are exceptions, (mostly made in Europe, or here for the European market) that have manual safeties, hand ejector revolvers made in the United States have mechanical safeties that prevent an unintentional discharge unless the trigger is deliberately pulled and held backward while the hammer falls. Colt was one of the first to offer this feature in 1908. Smith & Wesson incorporated a positive hammer block safety in 1945. Taurus and Ruger revolvers both have transfer-bar safeties.
But if you cock the hammer and pull the trigger, intentionally or not, the gun will do what it's supposed to do and fire. No safety can protect a user from being careless or stupid.