Sayyiduna Ibn Abbas (may Allah be pleased with them both) said: The Messenger of Allah (peace and blessings be upon him) combined the Zuhr and Asr prayers in Madinah, though there was neither travel nor fear. (The narrator Sa'id bin Jubayr said:) I asked Ibn Abbas (may Allah be pleased with them both): Why do you think he (peace and blessings be upon him) did that? He said: "He (peace and blessings be upon him) wanted not to put anyone of his Ummah in hardship."
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12463