Theravāda Vinayapiṭaka
Monks’ rules and their analysis
Monks’ Training (Sekhiya) 70
… in Anāthapiṇḍika’s monastery. Now at that time the group of six monks, standing, taught dhamma to (someone) who was sitting down … “…
‘I will not teach dhamma, standing, to (someone) who is sitting down (and) who is not ill,’ is a training to be observed.”
Dhamma should not be taught, standing, to (someone) who is sitting down (and) who is not ill … see Ch. 69 … if he is the first wrong-doer.