Vinaya Pitaka - Monastic Rules
Bhikkhu Vibhanga - Sekhiya 71: Not to teach the dhamma to someone who is walking ahead of you unless he is ill.
- Translated from the Pali by I.B. Horner.
… in Anāthapiṇḍika’s monastery. Now at that time the group of six monks, going behind, taught dhamma to (someone) going in front … " …
‘I will not teach dhamma, going behind, to (someone) going in front (and) who is, not ill,’ is a training to be observed."
Dhamma should not be taught, going behind … if he is the first wrong-doer.
1 tena samayena buddho bhagavā sāvatthiyaṃ viharati jetavane anāthapiṇḍikassa ārāme. tena kho pana samayena chabbaggiyā bhikkhū pacchato gacchantā purato gacchantassa dhammaṃ desenti … pe … .
2 "na pacchato gacchanto purato gacchantassa agilānassa dhammaṃ desessāmīti sikkhā karaṇīyā"ti. (71:216)
3 na pacchato gacchantena purato gacchantassa agilānassa dhammo desetabbo. yo anādariyaṃ paṭicca pacchato gacchanto purato gacchantassa agilānassa dhammaṃ deseti, āpatti dukkaṭassa.