Musannaf Ibn Abi Shayba 11:30

Ibn Fudayl 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 roam in Paradise wherever they wish. When they saw the excellence of their resting place, their food, and their drink, they said: 'Would that our people knew what Allah has done for us, so that they might desire Jihad and not turn away from it.' Allah the Exalted said: 'I will inform your brothers about you and convey [the message] to them.' So they rejoiced and were glad at that. That is the saying of Allah the Exalted: 'And do not think of those who have been killed in the way of Allah as dead; rather, they are alive with their Lord, receiving provision,' up to His saying: 'And that Allah does not waste the reward of the believers.'"