Musannaf Ibn Abi Shaybah

Ibrahim Taimi (may Allah have mercy on him) says that the souls of the martyrs take the form of green birds and roam in Hell. When they go towards the lanterns hanging from the Throne, Allah Almighty says to them three times: "Ask Me for whatever you wish." They say, "O our Lord! We ask You to send us back to the world so that we may fight once more in Your path."