Tena samayena buddho bhagavā sāvatthiyaṁ viharati jetavane anāthapiṇḍikassa ārāme.At one time the Buddha was staying at Sāvatthī in the Jeta Grove, Anāthapiṇḍika’s Monastery. Tena kho pana samayena chabbaggiyā bhikkhū pacchato gacchantā purato gacchantassa dhammaṁ desenti …pe….At that time the monks from the group of six were giving teachings to people walking in front of them. …

“Na pacchato gacchanto purato gacchantassa agilānassa dhammaṁ desessāmīti sikkhā karaṇīyā”ti.
desessāmīti → desissāmīti (bj)“‘I will not give a teaching to anyone walking in front of me who is not sick,’ this is how you should train.”

Na pacchato gacchantena purato gacchantassa agilānassa dhammo desetabbo.One should not give a teaching to anyone walking in front of oneself who is not sick. Yo anādariyaṁ paṭicca pacchato gacchanto purato gacchantassa agilānassa dhammaṁ deseti, āpatti dukkaṭassa.If a monk, out of disrespect, gives a teaching to someone walking in front of him who is not sick, he commits an offense of wrong conduct.

Anāpatti—There is no offense: asañcicca …pe…if it is unintentional; ādikammikassāti.if he is the first offender.

Ekādasamasikkhāpadaṁ niṭṭhitaṁ.The eleventh training rule is finished.