Imam Al-Nawawi’s Riyad-us-Saliheen
Chapter 344
Undesirability of offering optional Prayer after the announcement of Iqamah
1759. Abu Hurairah (May Allah be pleased with him) said: The Prophet (sallallaahu alayhi wa sallam) said, “When the Iqamah is called, no prayer should be performed except the obligatory prayer.”
[Muslim].