Mishnà su Levitico 14:47

If a person entered a house afflicted with a nega, carrying his clothes upon his shoulders, and his sandals and rings in his hands, both he and they become unclean immediately. If, however, he was wearing his clothes and had his sandals on his feet and his rings on his hands, he becomes unclean immediately, but they remain clean, unless he stayed as much time as is required for the eating of half a loaf of wheat bread and not of barley bread, while in a reclining posture and eating with some condiment.