Because, that would have made it more difficult for Israel to reap the spoils. Out of praise comes victory, and then only if it has been asked for. God forces on no one. If you asked someone for money in another state and then talked to them again on that day, you would not ask for the money again. You would thank them that it is on its way.
Unity is needed.
And when the day of Pentecost was fully come, they were all with one accord in one place. But fear came in early to separate us from those who could help us grow closer to God. And great fear came upon all the church, and upon as many as heard these things. First, acccept the Lord Jesus as your saviour. Second, allow His Holy Spirit to enter and rule in your life.