From:
Theravāda Vinaya Theravāda Collection on Monastic Law
Mahāvibhaṅga The Great Analysis
Sekhiyakaṇḍa The chapter on training
Pādukavagga The subchapter on shoes
63. Yānasikkhāpada 63. The training rule on vehicles
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 yānagatassa dhammaṁ desenti …pe…. At that time the monks from the group of six gave teachings to people in vehicles. …
“Na yānagatassa agilānassa dhammaṁ desessāmīti sikkhā karaṇīyā”ti. “‘I will not give a teaching to anyone in a vehicle who is not sick,’ this is how you should train.”
Yānaṁ nāma A vehicle:
vayhaṁ ratho sakaṭaṁ sandamānikā sivikā pāṭaṅkī. a wagon, a carriage, a cart, a chariot, a palanquin, a litter.
Na yānagatassa agilānassa dhammo desetabbo. One should not give a teaching to anyone in a vehicle who is not sick.
Yo anādariyaṁ paṭicca yānagatassa agilānassa dhammaṁ deseti, āpatti dukkaṭassa. If a monk, out of disrespect, gives a teaching to someone in a vehicle 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.
Tatiyasikkhāpadaṁ niṭṭhitaṁ. The third training rule is finished.