Is the pledging of a gifted item by a father valid if he gifted it to his son and retains the right to reclaim it?

Primary text

If a father pledges an object he has gifted to his son before revoking the gift, the pledge is invalid for the same reason stated above (pledging something not owned). The basis is that the father is pledging property over which he has no ownership, without the permission of the owner, and without any legal authority over it. This is analogous to a husband pledging half of the dower before consummation of the marriage.