Yong Fa wrote:I have a few questions about the five-year nissaya period that newly ordained bhikkhus undergo, during which they live in dependence on a teacher at a monastery.
1) Where are the origins of this practice in the Vinaya? Please provide a citation link if you can.
The details regarding nissaya are given in several sections of the Vinaya Piṭaka’s Mahāvagga and Cuḷavagga, but especially in the Nissayamuccanakakathā section of the former (Vin. i. 80) and the Niyassakamma section of the latter (Vin. ii. 7).Mahāvagga: Release from DependenceCūḷavagga: Act of GuidanceThanissaro’s Monastic Code, Nissaya Chapter
(includes elaboration from the Vinaya Commentaries)
Yong Fa wrote:2) Does this recommendation come from the Buddha himself or from a later commentator?
From the Buddha.
Yong Fa wrote:3) What is done during these five years? Monks have told me that it involves the study of the patimokkha and suttas, and it is likely that one would also study Pali during this time. I am curious if there is anything else done in this period,
The Vinaya doesn't lay down any kind of program for how the five years should be spent, but mainly concerns itself with laying down the duties of the pupil towards the teacher and the teacher towards the pupil, and stipulating what virtues are needed for a monk to be qualified to give nissaya and what are needed for a monk of five rains to be freed from nissaya (this isn't automatic — the saṅgha can insist on ten years in the case of an immature monk and even after ten years the release from nissaya may be revoked in the case of a badly behaved monk).
The absence of any program in the Vinaya means that each monastery or each sub-tradition will go about the training of a new monk in its own way.
Yong Fa wrote:and why five years is allotted.
No reason is given for prescribing this particular duration.