In the following passages Jesus makes it clear that buying and selling (unnecessarily) on the Sabbath is forbidden:

Nehemiah
13:15 In those days saw I in Judah [some] treading wine presses on the sabbath, and bringing in sheaves, and lading asses; as also wine, grapes, and figs, and all [manner of] burdens, which they brought into Jerusalem on the sabbath day: and I testified [against them] in the day wherein they sold victuals.
13:16 There dwelt men of Tyre also therein, which brought fish, and all manner of ware, and sold on the sabbath unto the children of Judah, and in Jerusalem.
13:17 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?
13:18 Did not your fathers thus, and did not our God bring all this evil upon us, and upon this city? yet ye bring more wrath upon Israel by profaning the sabbath.
13:19 And it came to pass, that when the gates of Jerusalem began to be dark before the sabbath, I commanded that the gates should be shut, and charged that they should not be opened till after the sabbath: and [some] of my servants set I at the gates, [that] there should no burden be brought in on the sabbath day.
13:20 So the merchants and sellers of all kind of ware lodged without Jerusalem once or twice.
13:21 Then I testified against them, and said unto them, Why lodge ye about the wall? if ye do [so] again, I will lay hands on you. From that time forth came they no [more] on the sabbath.
13:22 And I commanded the Levites that they should cleanse themselves, and [that] they should come [and] keep the gates, to sanctify the sabbath day. Remember me, O my God, [concerning] this also, and spare me according to the greatness of thy mercy.

Jeremiah
17:19 Thus said the LORD unto me; Go and stand in the gate of the children of the people, whereby the kings of Judah come in, and by the which they go out, and in all the gates of Jerusalem;
17:20 And say unto them, Hear ye the word of the LORD, ye kings of Judah, and all Judah, and all the inhabitants of Jerusalem, that enter in by these gates:
17:21 Thus saith the LORD; Take heed to yourselves, and bear no burden on the sabbath day, nor bring [it] in by the gates of Jerusalem;
17:22 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.
17:23 But they obeyed not, neither inclined their ear, but made their neck stiff, that they might not hear, nor receive instruction.
17:24 And it shall come to pass, if ye diligently hearken unto me, saith the LORD, to bring in no burden through the gates of this city on the sabbath day, but hallow the sabbath day, to do no work therein;
17:25 Then shall there enter into the gates of this city kings and princes sitting upon the throne of David, riding in chariots and on horses, they, and their princes, the men of Judah, and the inhabitants of Jerusalem: and this city shall remain for ever.
17:26 And they shall come from the cities of Judah, and from the places about Jerusalem, and from the land of Benjamin, and from the plain, and from the mountains, and from the south, bringing burnt offerings, and sacrifices, and meat offerings, and incense, and bringing sacrifices of praise, unto the house of the LORD.
17:27 But if ye will not hearken unto me to hallow the sabbath day, and not to bear a burden, even entering in at the gates of Jerusalem on the sabbath day; then will I kindle a fire in the gates thereof, and it shall devour the palaces of Jerusalem, and it shall not be quenched.