References – AN 10.31: Upāli 
Sutta / Aṅguttara Nikāya / AN 10: Dasakanipāta / AN 10.31: Upālisutta (1)

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Reflections by Ajahn Pasanno on the ten reasons the Buddha laid down training rules (AN 10.31). [Vinaya] [Pāṭimokkha] [Monastic life] // [Great disciples] [Saṅgha] [Communal harmony] [Faith]

Vinaya: Khandhaka 17.1.4: Upāli the barber ordains senior to the Sakyan princes. [Respect] [Conceit]

A Monastic's Life [2013], Session 1, Excerpt 7