Tithing here is not money set aside. It is giving to your own awareness the very qualities you claim to want, feeling yourself already to be the person who has them. The storehouse is that inner awareness, and the meat brought into it is the settled conviction that the wish is answered. You feed the house by living now in the state you desire.
The words prove me now are the one place Scripture invites a test. A person changes the assumption he carries, refuses the evidence of lack, and holds the feeling of the thing already his. When he does, the outer world reshapes itself to match, pouring back more than he can contain. The windows of heaven are not in the sky. They open the moment your inner conviction shifts, because a changed assumption always changes what your life expresses.