It is narrated from Sayyiduna Ibn Abbas (may Allah be pleased with them both); he said: "The Messenger of Allah (peace and blessings be upon him) prayed two rak'ahs between Makkah and Madinah, though he (peace and blessings be upon him) feared no one but Allah."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12805