Sayyiduna Jabir narrates: Sayyiduna Sa'd bin Abi Waqqas said to a man: "Your Friday prayer did not count." The Prophet (peace and blessings be upon him) asked: "Why is that, O Sa'd?" He replied: "Because he talked during your sermon." The Prophet (peace and blessings be upon him) said: "Sa'd spoke the truth."
Abu Ya'la and al-Bazzar recorded it; its chain contains Mujalid bin Sa'id, whom people declared da'if (weak), while according to one report al-Nasa'i (may Allah have mercy on him) declared him thiqah (trustworthy).
Hadith Referenceمجمع الزوائد ومنبع الفوائد / كتاب الصلاة / 3125