Sunan Abi Dawud Book 15, Hadith 43
Messenger of Allah, tell me about jihad and fighting. He replied: Abdullah ibn Amr, if you fight with endurance seeking from Allah your reward, Allah will resurrect you showing endurance and seeking your reward from Him, but, if you fight for vain show seeking to acquire much, Allah will resurrect you making a vain show and seeking to acquire much. In whatever you fight or are killed, Abdullah ibn Amr, in that state Allah will resurrect you.
‘Amr said “I heard from Abu Wa’il a tradition which surprised me, he then narrated the tradition to the same effect (as mentioned before).
The Prophet (ﷺ) said: When your brethren were smitten at the battle of Uhud, Allah put their spirits in the crops of green birds which go down to the rivers of Paradise, eat its fruit and nestle in lamps of gold in the shade of the Throne. Then when they experienced the sweetness of their food, drink and rest, they asked: Who will tell our brethren about us that we are alive in Paradise provided with provision, in order that they might not be disinterested in jihad and recoil in war? Allah Most High said: I shall tell them about you; so Allah sent down; "And do not consider those who have been killed in Allah's path." till the end of the verse.