Brahmajalasutta 1.3.5

1.3.5

Itihame ubho ācariyantevāsī aññamaññassa ujuvipaccanīkavādā bhagavantaṃ piṭṭhito piṭṭhito anubandhā honti bhikkhusaṅghañcā”ti.

And so both tutor and pupil followed behind the Buddha and the Saṅgha of mendicants directly contradicting each other.”