Edit: Found the sutta, SA205:
“At that time the Blessed One, having recited all of the verses of the Udāna , said to the venerable Ānanda:”
Not sure if this section has a Pāli counterpart.
I have a working theory that, this might refer to either the verse portions of Itivuttaka, or a corpus of materials that is the collection of Udānavargas from Sarvastivadin schools + Dhammapada. As per my work in this excel:
A complete Udāna compilation might be the obvious answer.
And there’s questions regarding whether Iti verses belong to Buddha or not. Some verses say “So said the Buddha”. But this is a common practice in (later?) poetic traditions, where the composer talks about themselves in the third person. This is a very common tradition in Farsi / Aryan poetry, for example.
And for example, many of the verses in Thig/Thag also refer to the composer in the third person. This is the such tradition I’m referring to.
The verses of Iti are meticulously composed, and in most cases the prose section can be reconstructed from the verse portions as is. This would explain why Buddha, being trained in Vedic metres, would compose these poems to help monks memorise the teachings.
It is possible as well, that verses were composed by brahmin disciples for similar reasons. But there’s quite a bit of lines in Iti that is repeated abundantly in suttas, other poetries and such. For example:
Dhāreti antimaṁ dehaṁ, jetvā māraṁ savāhinin’ti.
This is repeated in Thig 1.7, Thig1.10, Thig3.6, Thig4.1, Thag 20.1, SN21:12, SN21.4, SN21.5, ITI57, ITI62, AN4.16.
Itivuttaka verses all in all, would make sense to be recited in a single setting. As would DHP, perhaps, but combining all DHP / Udānavarga verses, which is about 50-60 chapters, around 500-600 verses in total, would perhaps be a stretch It would take about 2-3 hours all in all; not undoable, and early corpus of his verses might’ve been shorter than the texts we have now.
Anyway, those are some meditations on the verses of the canon. 