Sampasadaniyasutta 17.2

17.2

Idha, bhante, ekacco samaṇo vā brāhmaṇo vā ātappamanvāya …pe… tathārūpaṃ cetosamādhiṃ phusati, yathāsamāhite citte dibbena cakkhunā visuddhena atikkantamānusakena satte passati cavamāne upapajjamāne

It’s when some ascetic or brahmin—by dint of keen, resolute, committed, and diligent effort, and right application of mind—experiences an immersion of the heart of such a kind that with clairvoyance that is purified and superhuman, they see sentient beings passing away and being reborn—