Musannaf Ibn Abi Shayba 3:5772

Abu Bakr narrated to us, he said: Muhammad ibn Fudayl and Abu Mu'awiyah narrated to us, from al-A'mash, from 'Umarah ibn 'Umayr, from 'Abd al-Rahman ibn Yazid, he said: 'Abdullah said: "The prayer is not to be shortened except in Hajj or Jihad."