Reference for Eduyot 7:2

הֵעִיד רַבִּי צָדוֹק עַל צִיר חֲגָבִים טְמֵאִים, שֶׁהוּא טָהוֹר. שֶׁמִּשְׁנָה רִאשׁוֹנָה, חֲגָבִים טְמֵאִים שֶׁנִּכְבְּשׁוּ עִם חֲגָבִים טְהוֹרִים, לֹא פָסְלוּ צִירָן:

R. Tzaddok testified about the brine of unclean locusts that it is clean. For an earlier Mishnah (taught): Unclean locusts which were pickled with clean locusts do not invalidate their brine. [They were lenient in respect to unclean locusts not to forbid their admixture, for they have no blood, but only a kind of moistness. This was the first Mishnah. And the testimony of R. Tzaddok added to this Mishnah to say that it is clean. Not only does it not forbid its admixture, but it itself is clean.]

Mishnah Makhshirin