Musannaf Ibn Abi Shayba 3:1117

Hatim (Hafs) ibn Isma'il narrated to us, from Ja'far, from his father, who said: Ali ibn al-Husayn used to command the young boys to pray Dhuhr and Asr together, and Maghrib and Isha together. It would be said to him, "They are praying the prayer outside of its time." He would say, "This is better than them sleeping through them."