Musnad Ahmad 27:1518

Rawh narrated to us, Hammad ibn Salamah narrated to us, from Yunus, from al-Hasan, from Ibn Umar, from the Prophet, may Allah bless him and grant him peace, in what he narrates from his Lord, Blessed and Exalted is He, who said: "Any servant of My servants who goes out striving in My way, seeking My pleasure, I guarantee him that I will return him with whatever reward and spoils he has attained. And if I take his soul, I will forgive him, have mercy upon him, and admit him into Paradise."