Musnad Ahmad 27:1519

Rawh narrated to us, Ibn ‘Awn narrated to us, from Muhammad, from al-Mughirah ibn Salman, who said: Ibn ‘Umar said: "I memorized from the Prophet, may Allah bless him and grant him peace, ten rak'ahs: two rak'ahs before the morning prayer, two rak'ahs before the noon prayer, two rak'ahs after the noon prayer, and two rak'ahs after the sunset prayer, and two rak'ahs after the night prayer."