Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) narrated that the eighteen Companions of the Messenger of Allah (peace and blessings be upon him) who were martyred on the day of Badr, Allah placed their souls in Paradise in green birds that graze freely in Paradise. While they were in that state, their Lord looked upon them and said: O My servants! What do you desire? They said: O our Lord! There is nothing beyond this (that we could desire). He then says again: O My servants! What do you desire? And the fourth time they say: Return our souls to our bodies so that we may be killed again just as we were killed before.
Hadith Referenceالمعجم الكبير للطبراني / باب العين / 10428