Masruq narrates from Sayyiduna Abdullah bin Mas'ud (may Allah be pleased with him) that he was asked about the souls of the martyrs, and he said: We too asked about that: "Their souls are like green birds; they have lamps hanging from the Throne. They fly about wherever they wish, then return to those lamps. Allah Almighty turns towards them and asks: Do you want anything? They say: What could we want, when we fly about wherever we wish in Paradise? When they realise that they will keep being asked, they say: O Lord! We wish that You return our souls to our bodies so that we may be killed in Your path once more. When Allah Almighty sees that they have no need, they are left as they are." (b) In al-Muqri's narration: We asked Abdullah bin Mas'ud (may Allah be pleased with him) about this verse: "Do not think of those who have been killed in the path of Allah as dead; rather, they are alive with their Lord, receiving provision, rejoicing." [Surah Al Imran: 169-170] He said: We too asked about that.
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18518