Musnad Ahmad 27:1067

'Abd al-Razzaq narrated to us, Sufyan informed us, from Yahya, and 'Ubayd Allah ibn 'Umar, and Musa ibn 'Uqbah, from Nafi', from Ibn 'Umar: "That the Prophet, peace and blessings of Allah be upon him, when he was in a hurry in his travel, would combine the Maghrib and the 'Isha' prayers." And in some of their narrations: "He would delay them both until a quarter of the night had passed."