A sage of this generation teaches "one should not ask what is possible but what is necessary." Setting priorities in life is a Jewish necessity. Without priorities, one could spend their whole life working on issues that are not the main priority but rather only on the minor ones.
Moses is preparing the tribes for their eventual entry into the Land of Israel. Two and a half of the twelve tribes approach Moses requesting that they remain on the east side of the Jordan and not settle in Israel proper. Their justification? They were heavy with livestock and needed a large land area to properly tend their possessions.
Moses in part of his rebuke of the request said their priorities were off. These tribes were placing their flocks and physical possessions in greater priority than their children. Moses in his rebuke mirrors their request but switches the order of their request by placing the children before their livestock.
"The children of Gad and the children of Reuven approached Moses and said, 'Enclosures for the flock we shall build here for our livestock and cities for our children' . . . Moses said to them, 'Build for yourselves cities for your children and enclosures for your penning . . ." Numbers 32:16 & 24, from this week's double Torah portion, Numbers 30:2-36:13