Majjhima Nikaya 3:119
SUJATOYasmiṁ samaye, bhikkhave, bhikkhuno passaddhakāyassa sukhino cittaṁ samādhiyati, samādhisambojjhaṅgo tasmiṁ samaye bhikkhuno āraddho hoti, samādhisambojjhaṅgaṁ tasmiṁ samaye bhikkhu bhāveti, samādhisambojjhaṅgo tasmiṁ samaye bhikkhuno bhāvanāpāripūriṁ gacchati.
At such a time, a mendicant has activated the awakening factor of immersion; they develop it and perfect it.