Sayyiduna Ubadah bin al-Samit (may Allah be pleased with him) narrates: The Prophet (peace and blessings be upon him) used to say: "When I speak something to you, those of you who are present should convey it to those who are absent."
Al-Tabarani recorded it in al-Mu'jam al-Kabir, and its narrators have been declared trustworthy.
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب العلم / 592