[159] (69) Bhikkhus, a bhikkhu possessing two qualities is capable of benefiting others, but not himself. What two? Here, bhikkhus, a bhikkhu is not quick to comprehend wholesome teachings (kusalesu dhammesu); he is not one who retains the teachings he has heard; he is not one who examines the meaning of the teachings he has retained; and it is not the case that, having understood the meaning and understood the Dhamma, he practices in accordance with the Dhamma (dhammānudhammapaṭipanna). But he has kindly speech and a lovely manner of speaking; he is endowed with urbane speech that is distinct, flawless, and makes the meaning known; and he is one who instructs, exhorts, inspires, and gladdens his companions in the holy life (sabrahmacārī). Possessing these two qualities, bhikkhus, a bhikkhu is capable of benefiting others, but not himself.
English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.