Musnad Ahmad 33:28

'Abd al-Razzaq narrated to us, Ma'mar informed us, from Yahya ibn Abi Kathir, from Muhammad ibn 'Abd al-Rahman ibn Thawban, from Jabir ibn 'Abd Allah, who said: "The Messenger of Allah (peace and blessings of Allah be upon him) stayed in Tabuk for twenty days, shortening the prayer."