Is it farther or further?
late 15c., "to stammer, prattle," in Caxton's translation of "Reynard the Fox," probably from Middle Flemish tatelen "to stutter," parallel to Middle Dutch, Middle Low German, East Frisian tateren "to chatter, babble," possibly of imitative origin. The meaning "tell tales or secrets" is first recorded 1580s. Sense influenced by tittle. Related: Tattled; tattling.