Musnad Abu Ya'la al-Mawsili 49:6

Ishaq narrated to us, Sufyan narrated to us, from Damrah bin Sa'id al-Ansari, who heard Ubaydullah bin Abdullah bin Utbah saying: Umar went out on a day of Eid and asked Abu Waqid al-Laythi: "With what did the Messenger of Allah, may Allah bless him and grant him peace, recite on this day?" He said: "With 'Qaf' (Surah 50) and 'Iqtarabat' (Surah 54)."