sn.46.49 Saṁyutta Nikāya (Linked Discourses)

“Bhikkhus, as to internal factors, I do not see any other factor that is so helpful for the arising of the seven factors of enlightenment as this: careful attention. When a bhikkhu is accomplished in careful attention, it is to be expected that he will develop and cultivate the seven factors of enlightenment.” The rest as in §13.