Ad She’Ya’id Alav Yode’ah Ta’alumos

The Rambam in perek bais concludes ולעולם איני חוזר לדבר זה and I will never ever repeat this chet. Similarly in perek bais when the Rambam defines teshuva

ומה היא התשובה הוא שיעזוב החוטא חטאו ויסירו ממחשבתו ויגמור בלבו שלא יעשהו עוד

and what's more, skipping one line, ויעיד עליו יודע תעלומות he should invite Hakadosh Baruch Hu. The meforshim explain that l'ha'id in loshon hakodesh has two different meanings. One is to give testimony, one is to call someone else to bear witness. והעדתי בכם את השמים ואת הארץ meaning I call them to bear witness. So here it has that latter meaning, ויעיד עליו יודע תעלומות and he calls Hakadosh Baruch Hu yodeiah taalumos who can really measure the resolve a person possesses at that moment. So he calls Hakadosh Baruch Hu to bear testimony שלא ישוב לזה החטא לעולם that his resolve is such now that if only he'll sustain it, so he takeh never ever would repeat that chet. A footnote points out in one of his maamarim in Pachad Yitzchak that Rabbeinu Yonah doesn't entirely agree with the Rambam. In Rabbeinu Yonah's ikarei hateshuva, so ha'ikar hasheini is azivas hachet. Then ha'ikar hatishah asar is עזיבת החטא בהזדמן לו והוא בתוקף תאותו meaning Rabbeinu Yonah enumerates separately azivas hachet in the most trying and most challenging of circumstances. And his source for that is

ואמרו רבותינו זכרונם לברכה איזהו בעל תשובה אשר תשובתו מגעת עד כסא הכבוד

and it's quite clear from Rabbeinu Yonah, again we sort of our orientation in hilchos teshuva not surprisingly comes from the Rambam, but according to Rabbeinu Yonah the baseline for teshuva is that a person's azivas hachet, a person's resolve not to repeat the chet would cover most situations that he would find himself in. But l'moshal let's say you have someone who's a recovering alcoholic and then you're going to force him to attend a simcha and all his relatives and all his friends and there are open bars all over the place and it's going to be just an extremely, extremely difficult situation. So that's what Rabbeinu Yonah describes as ha'ikar hatishah asar which is a higher madreiga of teshuva but it's not indispensable for the basic madreiga of teshuva. The Rambam doesn't know of any such distinction. According to the Rambam when a person does teshuva it has to be that at that moment his resolve is such that even what Rabbeinu Yonah calls when he would be betokef taavoso in the most trying and provocative of situations that even then he would withstand and not repeat the chet.