Yevamot 90A

ואוכלת בגינו תרומה. בתרומה דרבנן. תא שמע: אכל תרומה טמאה ⁠— משלם חולין טהורים. שילם חולין טמאים, סומכוס אומר משום רבי מאיר: בשוגג ⁠— תשלומיו תשלומין, במזיד ⁠— אין תשלומיו תשלומין. וחכמים אומרים: אחד זה ואחד זה ⁠— תשלומיו תשלומין, וחוזר ומשלם חולין טהורין.

It was further taught: And she eats teruma on his account. The Talmud explains: This is referring to teruma that applies by rabbinic law, not by Torah law. The Talmud attempts to offer a proof for this claim. Come and hear a baraita: If a non-priest ate ritually impure teruma of a priest, he must pay him with ritually pure, non-sacred produce. In a case where he paid with impure, non-sacred food, Sumakhos says in the name of R' Meir that if he did so unwittingly, his payment is considered payment, but if he acted intentionally, his payment is not payment at all. And the Rabbis say: Both in this case and that one his payment is a valid payment, and the food has the sanctity of teruma, although it is ritually impure, and he must also go back and pay him again with pure, non-sacred food.

והוינן בה: במזיד אין תשלומיו תשלומין? תבא עליו ברכה, דאכל מיניה מידי דלא (ק)חזי ליה בימי טומאתו, וקא משלם מידי ד(ק)חזי ליה בימי טומאתו.

And we discussed this baraita with regard to the following question: Why is it that according to the opinion of R' Meir, when the non-priest pays the priest with ritually impure, ordinary food intentionally, his payment is not considered payment? On the contrary, the non-priest should be blessed, as he ate something of his that is not fit for him even during the priest’s days of impurity, as impure teruma must be burned, and he pays him with impure, ordinary food, which is something that is fit for him during his days of impurity. Admittedly, once he gives it to him, the produce becomes impure teruma, but at the time of his payment the food was available to be eaten.