Sayyiduna Abu Hurairah (may Allah be pleased with him) said: The Messenger of Allah (peace and blessings be upon him) said: "When the Iqamah for prayer is called, there is no prayer except the obligatory prayer."

With this chain, Sayyiduna Abu Hurairah (may Allah be pleased with him) narrated similarly from the Noble Prophet (peace and blessings be upon him).

Sayyiduna Ibn Buhaina (may Allah be pleased with him) said: The iqamah for prayer had been given when the Messenger of Allah (peace and blessings be upon him) noticed a man who was performing two units of Sunnah prayer. When the Prophet (peace and blessings be upon him) finished the prayer, the people surrounded that man. The Messenger of Allah (peace and blessings be upon him) said: "Are you performing four units of (Fajr) morning prayer?"

It is narrated from Sayyiduna Abu Hurairah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) said: "When the Iqamah for prayer is called (i.e., the Takbir), then there is no prayer except the obligatory prayer." Imam Darimi (may Allah have mercy on him) said: If one is praying at home and the Iqamah is called in the mosque, then this is relatively easier.