Nuaym ibn Masud was from Najd in the northern highlands of Arabia. He belonged to the powerful Ghatafan tribe. As a young man, he was clever and alert. He was full of enterprise and travelled widely. He was resourceful, every ready to take up a challenge and not prepared to allow any problem to get the better of him.
While in Yathrib, Nuaym was known to spend generously and he in turn would be lavishly entertained. In this way Nuaym came to develop strong links among the Jews of the city and in particular with the Banu Qurayzah.
He played an important part in the battle of Khandaq.
http://www.witness-pioneer.org/vil/Articles/companion/nuaym_ibn_masud.htm