Abdullah bin Abi Musa narrated: Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) came while the imam was leading the Fajr prayer, so he prayed two rak'ahs facing a pillar, because he had not yet prayed the Sunnah of Fajr.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 9353