Musa bin Salamah says: I asked Sayyiduna Ibn Abbas (may Allah be pleased with them both): I am in Makkah, so how should I pray? He said: "Pray two rak'ahs; this is the Sunnah of Abu al-Qasim (peace and blessings be upon him)."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12838