What did the Prophet Muhammad (peace be upon him) order when the Mu'adh-dhin pronounced the Adhan for Fajr prayer and the dawn became evident?
 Narrated Hafsa:                     When the Mu'adh-dhin pronounced the Adhan for Fajr prayer and the dawn became evident the Prophet ordered a two rak`at light prayer (Sunna) before the Iqama of the compulsory (congregational) prayer.