Musnad Ahmad 32:525

Yunus narrated to us, he said: Fulayh narrated to us, from Muhammad ibn Musahiq, from Amir ibn Abdullah—meaning Ibn al-Zubayr—from Anas, who said: "I have not seen an Imam whose prayer was more similar to the prayer of the Messenger of Allah (may Allah bless him and grant him peace) than this Imam of yours," referring to Umar ibn Abd al-Aziz, while he was in Medina at that time. And Umar used not to prolong the recitation.