Musnad Ahmad 1012:121

'Abdullah narrated to us, Abu Khaythama Zuhayr ibn Harb narrated to us, Jarir narrated to us, from Mansur, from Hilal ibn Yasaf, from Abu al-Muthanna, from the nephew of 'Ubadah, from 'Ubadah ibn al-Samit, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "There will be rulers over you who will be preoccupied by things away from the prayer, until they delay it past its time. So, pray it at its time." A man said: "O Messenger of Allah, if I catch it with them, should I pray?" He said: "If you wish."