Musnad Ahmad 32:333

'Abd al-Samad narrated to us, Hammad narrated to us, Thabit narrated to us, from Anas, that the Messenger of Allah (peace and blessings of Allah be upon him) said: "There is no soul that dies and has goodness with Allah, that would be pleased to return to the world, except for the martyr. For he would be pleased to return to the world and be killed once again, because of what he sees of the virtue of martyrdom."