Musnad Ahmad 27:671

Isma'il narrated to us, Ayyub informed us, from Nafi', that Ibn 'Umar was called upon for help regarding Safiyyah. He traveled during that night the distance of three nights' travel. He traveled until evening came, so I said: "The prayer." But he traveled and did not turn around. He traveled until it became dark, and Salim said to him: "Or a man, the prayer; you have reached the evening." He said: "Indeed, the Messenger of Allah (peace be upon him), when he was hurried in travel, would combine these two prayers." "And I intend to combine them, so travel on." He traveled until the twilight disappeared, then he descended and combined them.