俱舍論記 23.38

23.38

「此中煖法至亦能修故」者，此下別明行修、得修念住行相。此明煖法初修、後修。初修煖位，由此種姓先未曾得，初緣諦起勢力嬴劣，要同分者方能修故，不能傍修餘諦念行。後增進時，由此種姓先已曾得、已緣諦故，勢力強盛，不同分者亦能修故，故能傍修餘諦念行。夫順決擇皆順見道，見道位中唯法念住，故於初位現唯法念。故《婆沙》云「然順決擇分善根順見道故，初起位中現在皆唯修法念住（已上論文）。」後稍容豫於四念住隨應現修。又苦、集、道有色、受、心、及餘法故，具四念住；滅唯無為，但有法念。又增進位應言修十三念住，謂苦、集、道各四念住，滅諦唯法。不過四故，名修四念。

Regarding 'Herein, the dharma of Heat... because they are also able to cultivate': from this point down, the text distinguishes cultivation through activity (prayogabhāvanā) and cultivation through acquisition (prāptibhāvanā) of the applications of mindfulness (smṛtyupasthāna) and their aspects (ākāra). This explains the initial cultivation and subsequent cultivation of the dharma of Heat. In the stage of the initial cultivation of Heat, because this lineage (gotra) has never been attained before, and it arises initially observing the truths, its strength is feeble; only what is of the same category (sabhāga) can be cultivated, and therefore it cannot laterally cultivate the applications [of mindfulness] and aspects of the remaining truths. Later, when progressing, because this lineage has already been attained previously and has already observed the truths, its strength is robust; what is of a different category (visabhāga) can also be cultivated, and therefore it can laterally cultivate the applications [of mindfulness] and aspects of the remaining truths. In general, the factors leading to penetration (nirvedhabhāgīya) all accord with the path of seeing (darśanamārga); in the stage of the path of seeing, there is only the application of mindfulness to dharmas (dharma-smṛtyupasthāna), so in the initial stage, in the present [moment] only mindfulness of dharmas is cultivated. Hence the Vibhāṣā says: 'However, because the roots of good of the factors leading to penetration accord with the path of seeing, in the stage of their initial arising, in the present [moment] all of them cultivate only the application of mindfulness to dharmas' (end of śāstra passage). Later, being slightly more at ease, according to circumstances the four applications of mindfulness are cultivated in the present. Furthermore, because suffering, origination, and the path have form, sensation, mind, and other dharmas, they possess the four applications of mindfulness; cessation is solely unconditioned (asaṃskṛta), so it has only the mindfulness of dharmas. Furthermore, in the stage of progression, one should say that thirteen applications of mindfulness are cultivated, namely four applications of mindfulness for each of suffering, origination, and the path, while the truth of cessation is only dharmas. Because they do not exceed four, they are called cultivating the four applications of mindfulness.