Musnad Abu Ya'la al-Mawsili 160:240

'Abdullah ibn Salamah al-Basri narrated to us, Ash'ath ibn Barraz narrated to us, from al-Hasan, who said: When this verse was revealed: "Then you will surely be asked that Day about the pleasure," they said: "O Messenger of Allah, about what pleasure will we be asked, while our swords are upon our shoulders?" And he mentioned the hadith.