[3] In the Anguttara Nikaya, training in "higher virtue" includes following the Patimokkha, training in "higher mind" (sometimes simply referred to as "concentration") includes entering and dwelling in the four jhanas, and training in "higher wisdom" includes directly perceiving the Four Noble Truths or knowledge of destruction of the taints.
The Buddha's threefold training is similar to the threefold grouping of the Noble Eightfold Path articulated by Bhikkhuni Dhammadinna in Culavedalla Sutta ("The Shorter Set of Questions-And-Answers Discourse," MN 44): virtue (sīlakkhandha), concentration (samādhikkhandha), wisdom (paññākkhandha ).
Nagarjuna refers to it in his Letter to a Friend (Suhrllekha), verse 53: "One should always train (shiksha) in superior discipline (adhishila), superior wisdom (adhiprajna) and superior mind (adhicitta)"[6] vimutti ca anuttarā; Anubuddhā ime dhammā, gotamena yasassinā.
Iti buddho abhiññāya, dhammamakkhāsi bhikkhunaṃ; Dukkhassantakaro satthā, cakkhumā parinibbuto"ti.
Translated by Vajira & Story (1998) (boldface added for emphasis) as: These are the principles realized by Gotama the renowned; And, knowing them, he, the Buddha, to his monks has taught the Dhamma.