‏الصلاة : Hadeeth No:1566 Hafsa reported: When the dawn appeared, the Prophet of Allaah (sallAllaahu alayhi wa sallam) observed two rak'ahs (of Sunnah prayers)....

‏فضائل الصحابة‏ : Hadeeth No:5987 This hadith has been narrated on the authority of Hisham through another chain of transmitters....