Interpreting , the Gemara taught that until the time of Jacob, there was no illness (as one lived one's allotted years in health and then died suddenly). Then Jacob came and prayed, and illness came into being, as reports, "And one told Joseph, ‘Behold, your father is sick'" (reporting sickness for the first time in the Torah). Similarly, the Pirke De-Rabbi Eliezer reported that from the creation of the Heaven and earth until then, no person had ever become ill. Rather, they would remain fit until the time they were to die. Then, wherever they would happen to be, they would sneeze, and their souls would depart through their noses. But then Jacob prayed, seeking mercy from God, asking that God not take his soul until he had an opportunity to charge his sons and all his household. And then, as reports, "And one told Joseph, ‘Behold, your father is sick.'" Therefore, a person is duty bound to say "life!" after another sneezes.