English of Core Text: “And all that the unclean one (who touched a dead body) touches shall become unclean.” Why is this said? Because Scripture says “one slain by the sword,” teaching that the sword itself is unclean with seven-day uncleanness and one who touches it is unclean seven days… Therefore it is written “and the soul that touches him shall be unclean until the evening”: he transmits only evening uncleanness and does not transmit seven-day uncleanness to his fellow. Might he transmit by carrying (heset)? Scripture says “touches” — he transmits only by contact, not by carrying.
On the daf / in context: Sifrei derives the precise hierarchy of tumah levels from the verse: a corpse is avi avos ha-tumah; one who touches it becomes an av; one who touches that person becomes a vlad and is unclean only until evening; vessels transmit further by contact but the person who touched the corpse does not transmit seven-day tumah by mere carrying.
Type of Learning: Gezeirah shavah / Kal va-Chomer limiting (degrees of tumah)What Is Learned: Contact with one who touched a corpse produces only evening uncleanness; the verse blocks both seven-day transmission to another person and impurity by heset.