Vinaya Pitaka - Monastic Rules
Bhikkhu Vibhanga - Sekhiya 63: Not to teach the dhamma to someone who is inside a vehicle unless they are ill.
- Translated from the Pali by I.B. Horner.
… in Anāthapiṇḍika’s monastery. Now at that time the group of six monks taught dhamma to (someone) in a vehicle … " …
‘I will not teach dhamma to (someone) in a vehicle (and) who is not ill,’ is a training to be observed."
Vehicle means: a cart, a carriage, a waggon, a chariot, a palanquin, a sedan-chair.
Dhamma should not be taught to (someone) in a vehicle (and) who is not ill. Whoever out of disrespect teaches dhamma to (someone) in a vehicle (and) who is not ill, there is an offence of wrong-doing.
There is no offence if it is unintentional … if he is the first wrong-doer.
1 tena samayena buddho bhagavā sāvatthiyaṃ viharati jetavane anāthapiṇḍikassa ārāme. tena kho pana samayena chabbaggiyā bhikkhū yānagatassa dhammaṃ desenti … pe … .
2 "na yānagatassa agilānassa dhammaṃ desessāmīti sikkhā karaṇīyā"ti. (63:208)
3 yānaṃ nāma vayhaṃ ratho sakaṭaṃ sandamānikā sivikā pāṭankī.
4 na yānagatassa agilānassa dhammo desetabbo. yo anādariyaṃ paṭicca yānagatassa agilānassa dhammaṃ deseti, āpatti dukkaṭassa.