Majjhima Nikaya 4:99
SUJATOYathārūpe anāsane nisinnaṁ yathārūpe agocare carantaṁ yathārūpe pāpake mitte bhajantaṁ viññū sabrahmacārī pāpakesu ṭhānesu okappeyyuṁ, so tañca anāsanaṁ tañca agocaraṁ te ca pāpake mitte paṭisaṅkhā yoniso parivajjeti.
Reflecting rationally, they avoid sitting on inappropriate seats, walking in inappropriate neighborhoods, and mixing with bad friends—whatever sensible spiritual companions would believe to be a bad setting.