Musnad Ahmad 2:235

'Abd al-Malik ibn 'Amr narrated to us, Hisham ibn Sa'd narrated to us, from Zayd ibn Aslam, from his father, who said: I heard 'Umar ibn al-Khattab saying: "Why the *ramal* (brisk walking) now, and the uncovering of the shoulders, when Allah has established Islam and banished disbelief and its people? Nevertheless, we will not abandon anything that we used to do during the time of the Messenger of Allah, may Allah bless him and grant him peace."