Dutiyasoceyyasutta 2.2

2.2

Idha, bhikkhave, bhikkhu musāvādā paṭivirato hoti, pisuṇāya vācāya paṭivirato hoti, pharusāya vācāya paṭivirato hoti, samphappalāpā paṭivirato hoti.

It’s when a mendicant doesn’t use speech that’s false, backbiting, harsh, or nonsensical.