Dasuttarasutta

Suttapiṭaka · Dīghanikāya · Pāthikavagga · Vol. 11 · Section 384

[384] What two dhammas are hard to penetrate? Whatever cause (hetu) and whatever condition (paccaya) there is for the defilement of beings, and whatever cause and whatever condition there is for the purification of beings. These two dhammas are hard to penetrate.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.