This is from the Council of Trent: “no one ought to make use of that rash saying, one prohibited by the Fathers under an anathema – that the observance of the commandments of God is impossible for one that is justified.” (Session 6, Ch. 11).
Question: To what anathema are they referring? What council?
Perhaps this may be of help.
(1) Here’s the salient part of the paragraph in ch. 11 from Denzinger with (footnotes) and [parentheticals].
But no one, however much justified, ought to think himself exempt from the observance of the commandments [can. 20]; no one ought to make use of that rash saying, one prohibited by the Fathers under an anathema, that the observance of the commandments of God is impossible for one that is justified [can. 18 and can. 22; cf. n. 200]. “For God commands not impossibilities, but, by commanding, both admonishes thee to do what thou are able, and to pray for what thou art not able, and aids thee that thou mayest be able”; (Cf. St. Augustine,
On Nature and Grace, 43, 50) “whose commandments are not heavy” [1 Jn 5:3]; “whose yoke is sweet and whose burthen light.” [Mt 11:30] “For, whoso are the sons of God, love Christ; but they who love him, keep his commandments, as Himself testifies” [Jn 14:23]; which, assuredly, with the divine help, they can do.
(2) The Augustine quote reads: “God therefore does not command impossibilities; but in His command He counsels you both to do what you can for yourself, and to ask His aid in what you cannot do. Now, we should see whence comes the possibility, and whence the impossibility. This man says: “That proceeds not from a man’s will which he can do by nature.” I say: A man is not righteous by his will if he can be by nature. He will, however, be able to accomplish by remedial aid what he is rendered incapable of doing by his flaw.”
(3) Although it doesn’t say “Council” it cites “cf. n. 200” which in Denzinger is the Conclusion of the decrees of the Second Council of Orange in 529. Orange II is generally regarded (Denzinger) as an authoritative expression of the Catholic Faith which addressed issues of grace and freedom, and the relevant part of the Conclusion reads as follows with an anathama at the end: “According to the Catholic faith we also believe that after grace has been received through baptism, all baptized persons have the ability and responsibility, if they desire to labor faithfully, to perform with the aid and cooperation of Christ what is of essential importance in regard to the salvation of their soul. We not only do not believe that any are foreordained to evil by the power of God, but even state with utter abhorrence that if there are those who want to believe so evil a thing, they are anathema.”