The ones who listen to what is being said, and then follow the best of it. These are the ones whom God has guided, and these are the ones who possess intelligence.
Translation endnotes
[39:18] Knowing that those who abandoned the Quran would follow teachings called hadith, sunna, and ijma, God uses these words almost invariably with a negative connotation when they do not relate to the Quran. It is noteworthy, that the verse asking us to listen to different words does not use the word "hadith" but the word "qawl." God does not give even a single positive usage of hadith when it is used to denote human words. Isn't there a sign in this? See 33:38; 66:3 and 6:110.