Pathikasutta 2.18.12

2.18.12

agārasmā anagāriyaṃ pabbajito samāno ātappamanvāya padhānamanvāya anuyogamanvāya appamādamanvāya sammāmanasikāramanvāya tathārūpaṃ cetosamādhiṃ phusati, yathāsamāhite citte taṃ pubbenivāsaṃ anussarati; tato paraṃ nānussarati.

By dint of keen, resolute, committed, and diligent effort, and right application of mind, they experience an immersion of the heart of such a kind that they recollect that past life, but no further.