He reported that the Messenger of Allah ﷺ said, "Know that Paradise lies beneath the shade of swords."
ى، أن رسول الله ﷺ قال: واعلموا أن الجنة تحت ظلال السيوف.
Bukhari related it in Jihad and Expeditions (2818), and Muslim in Jihad and Expeditions (1742:20), both of them through Musa bin Uqba, from Salim Abu Nadr, the freed slave of Umar bin Ubaydullah and his scribe, who said that Abdullah bin Abu Awfa wrote to him, and he mentioned it. The wording given is that of Bukhari, and Muslim related it in full.