Musnad Ahmad 2:10

Hassan ibn Musa and Husayn ibn Muhammad narrated to us, they said: Shayban narrated to us, from Yahya, from Abu Salamah, from Abu Hurairah: That Umar ibn al-Khattab was delivering the sermon on a Friday when a man arrived. Umar said: "Why are you being detained from the prayer?" The man said: "It was only that I heard the call, so I performed ablution." He said: "And that too! Have you not heard that the Messenger of Allah, peace and blessings of Allah be upon him, said: 'When one of you goes to Friday [prayer], let him perform ghusl'?"