Majma al-Zawaid — Hadith 18203

Al-Hasan narrates: Sayyiduna Uthman bin Abi al-As (may Allah be pleased with him) had a house (perhaps a room is meant here) which he had set aside for conversation. He would spend one hour speaking about worldly matters and one hour about the Hereafter, and Allah knows best which of the two hours prevailed.
Al-Tabarani recorded it through two routes; the narrators of one of them are the narrators of the Sahih, except Muhammad bin Uthman bin Abi Safwan, who is thiqah (trustworthy).