How sound is the Hadith: "Whoever considers a believer ignorant, his sin be upon him"?

We have not come across a chain of narration (sanad) for this hadith to ascertain its authenticity or weakness. We found it in Lisan al-Arab, and subsequently in Nihayat al-Gharib and Dalil al-Falihin, but the authors did not mention a chain of narration for it. Therefore, we cannot rule on its authenticity or weakness.