Nafi' bin al-Azraq came to Sayyiduna Ibn Abbas (may Allah be pleased with them both) and asked: "Are the five prayers in the Qur'an?" He said: "Yes!" Then he recited this verse: "So glorify Allah when you reach the evening" [Surah al-Rum: 17] and said: "This is the Maghrib prayer"; "and when you reach the morning" [Surah al-Rum: 17]: "This is the Fajr prayer"; "and in the late afternoon" [Surah al-Rum: 18]: "This is the Asr prayer"; "and when you reach midday" [Surah al-Rum: 18]: "This is the Zuhr prayer." And he recited this verse: "And after the Isha prayer: three times of privacy for you" [Surah al-Nur: 58].
Hadith Referenceالسنن الكبرى للبيهقي / كتاب الصلاة / 1683