[520] For whomever the life faculty (jīvitindriya) arises, does the equanimity faculty (upekkhindriya) arise for him?
For those being reborn without equanimity, and, in the course of existence (pavatta), at the moment of arising of a mind (citta) dissociated from equanimity — the life faculty arises for them, but the equanimity faculty does not arise for them. For those being reborn with equanimity, and, in the course of existence, at the moment of arising of a mind associated with equanimity — for them both the life faculty arises and the equanimity faculty arises.
Or rather, for whomever the equanimity faculty arises, does the life faculty arise for him? — Yes.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.