It is clear that non-Jews were allowed to bring animals to the Temple for sacrifice (see, for example, the statement made by King Solomon at the dedication of the First Temple, I Melakhim 8:41-43). The question dealt with on today’s daf is whether their contributions for the upkeep of the Temple (referred to as bedek ha-bayit – see Sefer Melakhim II, Chapter 12) can be accepted.
The Gemara relates:
One baraita taught: In the case of a gentile who pledged a gift for Temple maintenance one accepts it from him, while another baraita taught: One does not accept it from him. Said Rabbi Ila in the name of Rabbi Yoḥanan: This is not difficult, the first applies to the beginning,the latter to the end. For Rabbi Asi said in the name of Rabbi Yoḥanan: In the beginning one should not accept from them even salt or water, whereas at the end one may not accept a thing that can be easily identified, but something that cannot easily be identified one may accept.
Rashi explains that at the beginning, when the Second Temple was under construction, the builders were not allowed to accept support from the non-Jews because there was suspicion about their intentions – that they may have planned to delay payment in the hope of convincing the Persian king to renege on the permission that he had granted allowing its construction – or concern that they would come to rely on those gifts and the Jewish community would not commit itself to the project as it should. After the Temple was completed, those concerns no longer existed and gifts to the Temple from non-Jews were welcomed.
The idea that an easily identified thing should not be accepted from non-Jews “even at the end” is explained by Rabbeinu Gershom as stemming from concern that the non-Jew may ask that it be returned at a later date. Others suggest that it is simply an embarrassment to the Jewish community that the Temple was built by others or that the non-Jew may point boastfully to their contribution, or to its importance for the Temple.