I’ve heard it said that there is a particular, late sutta, that appears to be an attempt at codifying the teachings of the Buddha , out of which the Abhidhamma grew. I can’t think which one, but I’m sure that someone will be able to point me to it.
I think you might be referring to DN 33 and DN 34.
DN 33 was given by Sariputta in response to the Jain leader Mahavira’s death, which lead to his followers descending into conflict about the right teachings. It’s clearly an attempt to codify the important teachings of the Buddha and is quite comprehensive.
DN 34 is similar and also given by Sariputta.
Later tradition claimed that the Abhidhamma goes back to Sariputta, so these suttas might have something to do with that claim.
The Abhidhamma (in Pali and in other traditions) is not a single entity of texts/teachings. One of the early Pali Abhidhammas is Vibhaṅga (= the Sarvāstivāda Dharmaskandha, T 26, No. 1537). The subject items of Vibhaṅga bear certain resemblances to the major structure of the so-called sutra-anga portion in the Saṃyutta-nikāya/Saṃyukta-āgama (See pp. 900, 923 in Choong Mun-keat’s “Ācāriya Buddhaghosa and Master Yinshun 印順 on the Three-aṅga Structure of Early Buddhist Texts” in Research on the Saṃyukta-āgama (Dharma Drum Institute of Liberal Arts, Research Series 8; edited by Dhammadinnā), Taiwan: Dharma Drum Corporation, August 2020, pp. 883-932). So, it seems there are several suttas on the particular teachings (subject items) on which the Abhidhamma may be based.
Yes, I’d just add that there’s an Abhidharma text in Chinese called the Sariputra Abhidharma, and it’s essentially a commentary on DN 33 (or the Dharmaguptaka’s version of it) that adds definitions to all of the items. That makes the connection pretty explicit. DA has parallels to both DN 33 and 34, and also another sutra like DN 34 that’s called Ekottara.
According to Analayo, there’s also Discourse on Explaining the Spheres (MĀ 86) which also gives a matrka list to be memorized by novices.
Also, according to Tse-Fu Kuan, the following Aṅguttara Nikāya sutras are also Abhidhamma style matikas (AN 3.25, AN 4.87–90, AN 9.42–51).
See: Tse-fu Kuan. Abhidhamma Interpretations of “Persons” (puggala): with Particular Reference to the Aṅguttara Nikāya. J Indian Philos (2015) 43:31–60 DOI 10.1007/s10781-014-9228-5