Sanhedrin 26A

ומיגנזו כולי עלמא. כי אתי, אמר ליה: ממאן נבעי?

And everyone would hide. When the head tax collector would arrive, R' Zeira’s father would say to him: From whom should I request taxes? The city is scarcely populated, and only a small sum of taxes should be imposed on it.

כי ניחא נפשיה, אמר להו: שקולו תליסר מעי דציירי לי בסדינאי, ואהדרו ליה לפלניא, דשקלתינהו מיניה ולא איצטריכו לי.

When he was dying, he said to those standing around his deathbed: Take 13 ma’a that are tied up in my sheet and return them to so-and-so, as I took them from him but I did not need them to pay the tax. Evidently, some tax collectors are God-fearing, and should not be disqualified.

אמר רבי שמעון: בתחילה היו קוראין אותן ״אוספי שביעית״.

§ The Mishnah teaches that R' Shimon said: Initially people would call them: Gatherers of the produce of the Sabbatical Year. Once the tax collectors grew abundant they would then call them: Merchants who trade in the produce of the Sabbatical Year.

מאי קאמר? אמר רב יהודה: הכי קאמר, בתחילה היו אומרים: אוספי שביעית ⁠– כשרין, סוחרין ⁠– פסולין.

The Talmud asks: What is he saying? What is R' Shimon teaching in this statement? Rav Yehuda says this is what he is saying: Initially the rabbis would say that gatherers of the produce of the Sabbatical Year, i.e., those who gather a large quantity of produce of the Sabbatical Year for themselves, are fit to bear witness, but merchants who trade in the produce of the Sabbatical Year are disqualified.

משרבו ממציאי מעות לעניים, ואזלי עניים ואספי להו ומייתו, חזרו לומר: אחד זה ואחד זה פסולין.

Once those who would offer money to the poor to gather produce for them grew abundant, and the poor would go and gather the produce for those who hired them and bring it to them, then gathering a large amount of produce of the Sabbatical Year was considered a business. The rabbis then said that both this category, gatherers of the produce of the Sabbatical Year, and that category, merchants who trade in the produce of the Sabbatical Year, are disqualified.