Musa bin Salamah says: We were with Sayyiduna Ibn Abbas (may Allah be pleased with them both) in Makkah, and we said: When we are with you, we pray four rak'ahs, and when we return to our lodgings, we pray two rak'ahs. He said: "That is the Sunnah of Abu al-Qasim (peace and blessings be upon him), even if it displeases you."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12839