Musannaf Ibn Abi Shayba 35:62

Ibn Mushir narrated to us, from Ibn Abi Layla, from ‘Ata’, from Jabir, who said: The Prophet, may Allah bless him and grant him peace, combined [the prayers] during the Battle of Tabuk between Dhuhr and ‘Asr, and between Maghrib and ‘Isha’.