Theravāda Vinayapiṭaka

Monks’ rules and their analysis

Monks’ Training (Sekhiya) 71

… 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.