It is narrated from Hazrat Ibn Buhaina (may Allah be pleased with him) that once the Noble Prophet (peace and blessings be upon him) saw a man performing the two Sunnah rak'ahs of Fajr at a time when the congregational prayer had already begun. After the prayer, the Noble Prophet (peace and blessings be upon him) said: Do not make this prayer like the Zuhr prayer, in which the rak'ahs before and after are joined together; rather, make a separation between them.