Sayyiduna Abu Barzah (may Allah be pleased with him) narrates that the Prophet (peace and blessings be upon him) said: "The example of the one who teaches people goodness and forgets himself is like the wick of a lamp, which gives light to people and burns itself."
Tabarani recorded it in al-Mu'jam al-Kabir; its chain contains Muhammad bin Jabir al-Suhaymi, who is da'if (weak) because of his poor memory and his mental confusion (ikhtilat).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب العلم / 869