Yasar narrates: Once, Abdullah bin Umar (may Allah be pleased with them both) saw me performing (nafl) prayer after the true dawn had appeared, so he threw pebbles at me and said: "O Yasar! How many rak'ahs have you performed?" I replied: I do not remember. So he said: "You do not understand. Once, the Prophet Muhammad (peace and blessings be upon him) came to us while we were performing this prayer (i.e., nafl at this time), and the Prophet (peace and blessings be upon him) expressed intense displeasure at us and said: Let all those present convey this to those who are absent: After the true dawn has appeared, only two rak'ahs (of sunnah) may be performed."

Yasar narrates: Once, Abdullah bin Umar (may Allah be pleased with them both) saw me performing voluntary prayers after the true dawn had appeared. Abdullah bin Umar (may Allah be pleased with them both) said: "O Yasar! Once the Prophet Muhammad (peace and blessings be upon him) came to us while we were performing this same prayer (i.e., voluntary prayers at this time), and he said: Let all people convey this message to those present and those absent: After the true dawn has appeared, only two rak'ahs (the Sunnah) may be performed (no other prayer can be performed at this time)."

Sayyiduna Abdullah bin Amr (may Allah be pleased with him) narrates: The Noble Prophet (peace and blessings be upon him) said: "After the true dawn has appeared, no prayer can be performed except the two rak‘ahs of Sunnah."