AN5.59: Paṭhamavuḍḍhapabbajitasutta

“Bhikkhus, it is rare to find one gone forth in old age who possesses five qualities. What five? It is rare to find one gone forth in old age (1) who is astute; (2) who has the proper manner; (3) who is learned; (4) who can speak on the Dhamma; and (5) who is an expert on the discipline. It is rare to find one gone forth in old age who possesses these five qualities.”