The Messenger of Allah ﷺ said, "The example of a scholar who teaches people what is good but forgets himself is like a lamp that gives light to people while burning itself away."
عن رسول الله ﷺ قال: مثل العالم الذي يعلم الناس الخير وينسى نفسه كمثل السراج يضيء للناس ويحرق نفسه.
Tabarani related it in Al-Kabir (2/178) from Ahmad bin Mualla Dimashqi and Hasan bin Ali Mamari, who both said, Hisham bin Ammar told us, Ali bin Sulayman Kalbi told us, Amash told me, from Abu Tamima, from Jundab bin Abdullah Azdi, a companion of the Prophet ﷺ, who said, then he mentioned it.In this chain is Ali bin Sulayman Kalbi, who is unknown. Haythami mentioned it in Al-Majmu (1/184-185) and said, "Its narrators are trustworthy," relying on Ibn Hibban, for in the chain is Ali bin Sulayman Kalbi, whom Ibn Hibban mentioned in his Thiqat (7/213) and said, "He relates unusual reports." Then Haythami, when discussing another hadith transmitted through Ali bin Sulayman Kalbi, said in Al-Majmu (6/232), "I do not know Ali bin Sulayman Kalbi."This hadith is strengthened by what has been narrated as a stopped report from Jundab bin Abdullah. Ahmad related it in Al-Zuhd (1127), and Abu Dawud related it in Al-Zuhd (392), both from the hadith of Hammad bin Salama, who said, Jareeri told us, from Abu Sawwar Adawi, that they came to Jundab, and he mentioned something similar. Hammad bin Salama is among those who heard from Jareeri before his memory became confused. Through these two chains, the hadith rises to the level of hasan, and indeed Munziri graded it hasan in Al-Targheeb wal-Tarheeb (220).