The Burden of Melachot Shabbat OR Why we care about carrying

(1) There are two [types of] transfers on Shabbat which amount to four inside, and two which amount to four outside. How so? [This is illustrated by] a poor person standing outside and a homeowner [standing] inside: [If] the poor person reaches his hand inside and puts [something] into the hand of the homeowner, or takes [something] from [the hand] and brings it outside, the poor person is liable and the homeowner is exempt. [If] the homeowner reaches his hand outside and puts [something] into the hand of the poor person, or takes [something] from [the hand] and brings it inside, the homeowner is liable and the poor person is exempt. [If] the poor person reaches his hand inside and the homeowner takes [something] from it, or puts [something] into it, and [the poor person] brings it outside, they are both exempt. [If] the homeowner reaches his hand outside and the poor person takes [something] from it, or puts [something] into it, and [the homeowner] brings it inside, they are both exempt.

(15) In those days saw I in Judah some treading winepresses on the sabbath, and bringing in heaps of corn, and lading asses therewith; as also wine, grapes, and figs, and all manner of burdens, which they brought into Jerusalem on the sabbath day; and I forewarned them in the day wherein they sold victuals. (16) There dwelt men of Tyre also therein, who brought in fish, and all manner of ware, and sold on the sabbath unto the children of Judah, and in Jerusalem. (17) Then I contended with the nobles of Judah, and said unto them: ‘What evil thing is this that ye do, and profane the sabbath day?

(21) thus saith the LORD: Take heed for the sake of your souls, and bear no burden on the sabbath day, nor bring it in by the gates of Jerusalem; (22) neither carry forth a burden out of your houses on the sabbath day, neither do ye any work; but hallow ye the sabbath day, as I commanded your fathers;