"Have you not considered the assembly [of leaders]," meaning: the nobles, "of the Children of Israel after Moses, when they said to a prophet of theirs, 'Raise for us a king, [that] we may fight in the way of Allah.'"
Muhammad said: The recitation is "nuqatil" (that we may fight) in the jussive mood; as a response to the request.
Al-Kalbi said: The Children of Israel remained for a long period of time without a king over them, so they desired to have a king over them who would fight their enemy. They went to a prophet of theirs from the descendants of Aaron, who was called Samuel, and said to him, "Raise for us a king, [that] we may fight in the way of Allah." Their prophet said to them, "Would you perhaps, if fighting was prescribed for you, not fight?" They said, "And why should we not fight in the way of Allah when we have been driven out from our homes and our children?" Their enemy was from the people of Goliath. "But when fighting was prescribed for them, they turned away, except for a few of them." [Verses 246-248]