Sahih Muslim 1884
The Book on Government
The High Positions that Allah has prepared for the Mujahid in Paradise
It has been narrated on the authority of Abu Sa`id al-Khudri that the Messenger of Allah (ﷺ) said (to him): Abu Sa`id, whoever cheerfully accepts Allah as his Lord, Islam as his religion and Muhammad as his Messenger is necessarily entitled to enter Paradise. He (Abu Sa`id) wondered at it and said: Messenger of Allah, repeat it for me. He (the Messenger of Allah) did that and said: There is another act which elevates the position of a man in Paradise to a grade one hundred (higher), and the elevation between one grade and the other is equal to the height of the heaven from the earth. He (Abu Sa`id) said: What is that act? He replied: Jihad in the way of Allah! Jihad in the way of Allah!