Qatadah (may Allah have mercy on him) says concerning the saying of Allah "And establish prayer at the two ends of the day" [Surah Hud: 114]: It means the morning and Asr prayers; and "and in the early hours of the night" [Surah Hud: 114] means the Maghrib and Isha prayers.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1687