Majjhima Nikaya 5:36
SUJATONanu mayā, moghapurisa, anekapariyāyena antarāyikā dhammā antarāyikā vuttā? Alañca pana te paṭisevato antarāyāya.
Haven’t I said in many ways that obstructive acts are obstructive, and that they really do obstruct the one who performs them?