Musnad Ahmad 30:1247

Abu Bakr al-Hanafi narrated to us, al-Dahhak bin Uthman narrated to us, from Bukayr bin Abdullah bin al-Ashajj, from Sulayman bin Yasar, from Abu Hurayrah, that he said: "I have not seen a man whose prayer was more similar to the prayer of the Messenger of Allah, peace and blessings of Allah be upon him, than so-and-so," referring to an Imam who was in Medina. Sulayman bin Yasar said: "So I prayed behind him, and he used to lengthen the first two rak'ahs of Dhuhr and shorten the last two, and he would shorten the Asr, and he would recite in the first two rak'ahs of Maghrib from the short chapters of the Mufassal, and he would recite in the first two rak'ahs of Isha from the medium chapters of the Mufassal, and he would recite in the morning prayer from the long chapters of the Mufassal." Al-Dahhak said: "And someone who heard Anas bin Malik narrated to me, saying: 'I have not seen anyone whose prayer was more similar to the prayer of the Messenger of Allah, peace and blessings of Allah be upon him, than this young man,' meaning Umar bin Abdul Aziz." Al-Dahhak said: "So I prayed behind Umar bin Abdul Aziz, and he used to do just as Sulayman bin Yasar said."