[158] [68] Bhikkhus, possessing two qualities, a bhikkhu is capable of benefiting himself, but not others. What two? Here, bhikkhus, a bhikkhu is not quick to grasp wholesome teachings, nor is he one who retains the teachings he has heard; but he is one who examines the meaning of the teachings he has retained, and, having understood the meaning and understood the Dhamma, he is one who practises in accordance with the Dhamma; yet he is not one of kindly and convincing speech (kalyāṇavāca) … capable of conveying the meaning; nor is he one who instructs … his companions in the holy life. Possessing these two qualities, bhikkhus, a bhikkhu is capable of benefiting himself, but not others.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.