Sayyiduna Abdullah bin Abbas (may Allah be pleased with them both) said that the Messenger of Allah (peace and blessings be upon him) said: "When your brothers were martyred on the day of Uhud, Allah placed their souls inside green birds, which fly about over the rivers of Paradise and eat of its fruits; beneath the Throne, lanterns of gold are hung for them, in which they dwell. When they found such food and drink and such a fine resting place, they said: 'Who will convey our message to our brothers, that we are alive in Paradise and are given provision, so that they do not lose their desire for jihad and do not show cowardice at the time of battle?' Allah, the Lord of Might, said: 'I will convey your message to them.'" Allah says: "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." [Surah Al Imran: 169]
Hadith Referenceالسنن الكبرى للبيهقي / كتاب السير / 18520