Tractate Tahorot - Chapter 5 - Mishnah 3 טהרות פרק ה׳ משנה ג׳

If there were two paths, the one unclean and the other clean, and one walked on one of them and then prepared clean foods which were then eaten and, then he was sprinkled upon once and a second time and he performed immersion and became clean, then he walked on the second path and then prepared clean foods, the latter are clean. If the first foods were still in existence both must be held in suspense. If he had not become clean in the meantime, the first is held in suspense and the second must be burnt.