Bāhiraṅgasutta

Suttapiṭaka · Saṁyuttanikāya · Mahāvaggasaṁyutta · Vol. 19 · Section 520

[520] Bhikkhus, taking it as an external factor, I do not see any other single factor for the arising of the seven factors of awakening (bojjhaṅga) like this: good friendship (kalyāṇamittatā). Bhikkhus, for a bhikkhu who has a good friend it may be expected that he will develop the seven factors of awakening, that he will cultivate the seven factors of awakening.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.

This passage also appears in 1 other place

Vol. 19 · Section 412 — Paṭhamasūriyūpamasutta