הלכה אויף דברים 10:2

(6) And all that we have written applies even if he speaks demeaningly of his friend to him [alone]. But if he joins himself to a company of men of wickedness and speakers of lashon hara in order to speak to them demeaningly of his friend or to hear [such words] from them, he transgresses also (Devarim 10:20): "And to Him shall you cleave," which Chazal explain as cleaving to Torah scholars, frequenting their assemblies in all circumstances — even eating and drinking with Torah scholars and doing business with them and joining them in all types of activities — all this, in order to learn from their deeds. Therefore, certainly, one who does the opposite of this, joining himself to a company of wicked men, transgresses this positive commandment.