Narrated `Aisha: Allah's Apostle used to pray two light rak`at before the morning (compulsory) prayer after the day dawned and the Mu'adh-dhin had finished his Adhan. He then would lie on his right side till the Mu'adh-dhin came to pronounce the Iqama.
Hadith Referenceصحيح البخاري / كتاب الأذان / 626
Hadith Gradingمحدثین:أحاديث صحيح البخاريّ كلّها صحيحة