Musnad Abu Ya'la al-Mawsili 228:3

Muhammad ibn Bashar narrated to us, Muhammad narrated to us, Shu'bah narrated to us, from al-Azraq ibn Qays, from Abdullah ibn Rabah, from a man among the companions of the Prophet (peace and blessings of Allah be upon him): That the Prophet (peace and blessings of Allah be upon him) prayed the Asr prayer, then a man stood up to pray. Umar saw him and said to him, "Sit down, for the People of the Book were only destroyed because there was no interval between their prayers." The Messenger of Allah (peace and blessings of Allah be upon him) said, "Ibn al-Khattab has done well."