Mishnayos Taharos Perek 2 Mishnah 5

First, second and third [degrees of uncleanness] in holy foods are unclean and convey uncleanness; Fourth [degree of uncleanness] is invalid and causes no uncleanness; And fifth [degree of uncleanness] may be eaten in a dish containing holy food.

הָרִאשׁוֹן וְהַשֵּׁנִי וְהַשְּׁלִישִׁי שֶׁבַּקֹּדֶשׁ, טְמֵאִין וּמְטַמְּאִין. הָרְבִיעִי, פּוֹסֵל וְלֹא מְטַמֵּא. וְהַחֲמִישִׁי, נֶאֱכָל בִּנְזִיד הַקֹּדֶשׁ: