سنن ابن ماجه

It was narrated from Abu Hurairah that the Messenger of Allah (ﷺ) said: “The likeness of the one who sits and listen to wisdom then only speaks of the bad things that he had heard, is that of a man who comes to a shepherd and says: “O shepherd, give me one of your sheep to slaughter,” and (the shepherd) says: “Go and grab the ear of the best of them.” Then he goes and grabs the ear of the sheepdog.’”

Another chain reports a similar hadith.