Is voluntary prayer permissible after the Imam sits on the pulpit on Friday?

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Voluntary prayer ceases immediately upon the Imam sitting on the pulpit. Only the person entering the mosque is permitted to pray the greeting of the mosque (Tahiyat al-Masjid), and that prayer should be brief. This ruling is established based on the narration from Tha'labah ibn Abi Malik, stating that during the time of Umar ibn al-Khattab, people prayed until Umar emerged. Once Umar sat on the pulpit and the muezzins gave the call to prayer, the people sat and conversed until the muezzin fell silent and Umar stood up, at which point everyone became silent. This indicates the widespread acceptance of this practice among them.