Pariyāyasutta

Suttapiṭaka · Saṁyuttanikāya · Mahāvaggasaṁyutta · Vol. 19 · Section 564

[564] Bhikkhus, whatever is tranquility (passaddhi) of body, that too is the tranquility factor of awakening (passaddhi-sambojjhaṅga); whatever is tranquility of mind (citta), that too is the tranquility factor of awakening. Thus does this come into the summary designation "the tranquility factor of awakening." In this way, by this method, it becomes twofold.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.