Talmud (Rodkinson)/Seder Moed/Tractate Shabbat 3 a
And he rejoined: Such transfers as involve the obligation of a sin-offering are counted; but those that do not involve such an obligation are not counted.
"They are both free." Was not the act (of transfer) committed by both? Said R. Hyya bar Gamda: The act of removing the thing was committed by the joint efforts of both, and they (the rabbis) said: "It is written in the law, when a person did it"4--i.e., when one person commits the act he is culpable, but when an act is committed by the joint efforts of two persons, they are both free.
Rabh questioned Rabbi: If one were laden by his friend with eatables and beverages and carried them outside (of the house), how is the law? Is the removing of his body tantamount to the removing of a thing from its place, and therefore he is culpable, or is it not so?