Musnad Ahmad 5:348

Abu Mu'awiyah narrated to us, Al-A'mash narrated to us, from Muslim ibn Sabih, from Shutayr ibn Shakl, from Ali, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said on the day of the Confederates (Al-Ahzab): "They distracted us from the middle prayer, the afternoon prayer (Asr). May Allah fill their graves and their houses with fire." He said: Then he prayed it between the two evening prayers, between Maghrib and Isha. And Abu Mu'awiyah said once: Meaning between Maghrib and Isha.