וְהַכֹּהֲנִים הַלְוִיִּם בְּנֵי צָדוֹק אֲשֶׁר שָׁמְרוּ אֶת מִשְׁמֶרֶת מִקְדָּשִׁי בִּתְעוֹת בְּנֵי יִשְׂרָאֵל מֵעָלַי הֵמָּה יִקְרְבוּ אֵלַי לְשָׁרְתֵנִי וְעָמְדוּ לְפָנַי לְהַקְרִיב לִי חֵלֶב וָדָם נְאֻם אֲדֹ-נָי ה’
The priests – the Levites, the sons of Tzadok – who kept the charge of My sanctuary when the children of Israel went astray from Me, they will come near to Me to minister to Me, and they will stand before Me to offer to Me the fat and the blood, says the L-rd Hashem.
“Sons of Tzadok?” But everyone knows that the kohanim (priests) are the descendants of Aaron! Actually, Rashi explains that Tzadok was the High Priest when Solomon built the Temple. (Tzadok anointed Solomon way back in I Kings chapter 1.) Later High Priests were his descendants, which is why the kohanim are called by his name.