(a) Musa bin Salamah said: I asked Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both): "I stay in Makkah; how should I pray?" He said: "Praying two rak'ahs is the Sunnah of the Prophet (peace and blessings be upon him)."
(b) Amr bin Marzuq (narrates that he) said: I asked Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both): "How much should I pray when I miss the prayer in al-Masjid al-Haram?" He said: "Two rak'ahs; that is the Sunnah of Abu al-Qasim (peace and blessings be upon him)."
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 5485