Messenger of Allah (S) said: "When one of you prays the two Rak'ah of Fajr then let him lay down on his right (side)."  

قَالَ رَسُولُ اللَّهِ ﷺ إِذَا صَلَّى أَحَدُكُمْ رَكْعَتَىِ الْفَجْرِ فَلْيَضْطَجِعْ عَلَى يَمِينِهِ قَالَ وَفِي الْبَابِ عَنْ عَائِشَةَ