This fragment is divided into three phrases.  Most editors agree that Aristotle is quoting or paraphrasing from memory.

The last phrase, καὶ πάντα κατ' ἔριν γίνεσθαι (all things come about by strife), is most likely a paraphrase of B80.

The middle phrase, ἐκ τῶν διαφερόντων καλλίστην ἁρμονίαν (the finest attunement stems from things bearing in opposite directions), Marcovich argues, is most likely a paraphrase of B51.

The first phrase is not attested for elsewhere.  Robinson noticed the Ionic word ἀντίξουν (opposes) and argued from this that the first phrase contains Heraclitus's actual words.