Musnad Abu Ya'la al-Mawsili 110:4

Uthman ibn Abi Shaybah narrated to us, Abdullah ibn Idris al-Awdi narrated to us, from Muhammad ibn Ishaq, from Isma'il ibn Umayyah, from Abu al-Zubayr, from Sa'id ibn Jubayr, from Ibn Abbas, who said: The Messenger of Allah (peace and blessings of Allah be upon him) said: "When your brothers were struck at Uhud, Allah placed their souls in the bellies of green birds that frequent the rivers of Paradise, eat from its fruits, and nest in lanterns of gold hanging in the shade of the Throne. When they found the goodness of their food, their drink, and their resting place, they said: 'Who will convey to our brothers on our behalf that we are alive in Paradise, being provided for, so that they do not refrain from war and do not turn away from Jihad?' He said: So Allah said: 'I will convey [the message] to them on your behalf.' Then Allah, Blessed and Exalted is He, revealed: 'And do not think of those who have been killed in the way of Allah as dead; rather, they are alive with their Lord, being provided for.'"