Hard to Find (1)
Dullabha Sutta  (AN 5:59)

“Monks, these five qualities are hard to find in one who has gone forth when old. Which five? It is hard to find one who has gone forth when old who is subtle, hard to find one who is consummate in his comportment, hard to find one who is learned, hard to find one who can teach the Dhamma, hard to find one who has mastered the Vinaya.”