Nuʿaym among Banū Qurayẓah

So Nuʿaym (may Allah be pleased with him) left, and he went to the Jews of Banū Qurayẓah. Now, the thing here with Nuʿaym is that he had good relations with the Jews, good relations with Quraysh, and, since he was from Ghaṭafān, he had good relations with his people. Nuʿaym ibn Masʿūd (may Allah be pleased with him) was a well-known man, a trusted man. So he went to Banū Qurayẓah and he told them, "You know me, and I know you, and you know our friendship. And you know that I would only give you a sincere advice. What you have done is wrong. You have decided to fight against Muḥammad (peace be upon him), but you are living in Madīnah. Your women and children and property are here, while Quraysh and Ghaṭafān are coming over to fight, but their women, children and property are somewhere else. Now Quraysh and Ghaṭafān are going to try to seize the opportunity to defeat Muḥammad, but if that opportunity doesn't arise, they're going to pack up and leave. And you know what will happen if they leave? Muḥammad will attack you first, since you are right there with him in Madīnah, and you know that you can't face off alone against Muḥammad."

They said, "Well, what you're saying is true. What shall we do?" He said, "You want to make sure that Quraysh and Ghaṭafān are willing to fight until the end, until you achieve the objective. Not just try to win and, if it doesn't work out, then they leave. No, you want to make sure that they will stay behind and fight with you, and not betray you and leave." They said, "All right; well, tell us how we can guarantee that." He said, "Ask them to leave some of their men with you as assurance," meaning that you take some of their men as hostages.

And this was a practice that existed in those days. A man could borrow money and then he could leave his child as a security. So it wasn't something that was strange; it did exist in those days. So Nuʿaym here is saying: ask them to hand over some of their men, both from Quraysh and from Ghaṭafān, and hold them with you as an assurance, as a guarantee that they're going to fight until the end. They said, "That's a good idea. We agree; we'll do that."