Digha Nikaya 1:344
SUJATOTasmātihānanda, dhammādāsaṁ nāma dhammapariyāyaṁ desessāmi, yena samannāgato ariyasāvako ākaṅkhamāno attanāva attānaṁ byākareyya:
So Ānanda, I will teach you the explanation of the Dhamma named ‘the mirror of the teaching’. A noble disciple who has this may declare of themselves: