"Rejoicing in what Allah has given them of His bounty," meaning: of martyrdom and provision. "And they receive good tidings about those who have not yet joined them from those who are behind them." The verse means: some of them say to others: We have left our brethren—so-and-so, and so-and-so, and so-and-so—fighting the enemy; they will be killed, if Allah wills, and they will attain provision, honor, and security.
Yahya [narrated] from Khalid, from Abu Abd al-Rahman, from Abu Salih, from Ibn Abbas, who said: "When the souls of the people of Uhud arrived to Allah, they were placed in the crops of green birds."