Abdullah bin Shaqiq narrates: One day Ibn Abbas (may Allah be pleased with them both) addressed us after Asr until the sun set and the stars appeared, and the people began calling out for the prayer; among the people was a man from Banu Tamim who was calling out. So Ibn Abbas (may Allah be pleased with them both) said: "Are you teaching me the Sunnah? May your mother lose you! I saw the Messenger of Allah (peace and blessings be upon him) combine Asr and Zuhr, and Maghrib and Isha." The narrator said: Then I met Abu Hurayrah (may Allah be pleased with him), and he too confirmed it.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 12860