Is it permissible to revoke a gift after waiving the inheritance – represented by a house and money – and taking possession of it, despite not knowing the exact value of the gifted money, and based on the Maliki school of thought which permits the gifting of an unknown amount?

There is no harm in adopting the Maliki school's view on the aforementioned issue, given that the questioner is a follower of this school and has been given a fatwa according to it. Furthermore, this view is preponderant and has been chosen by some scrutinizing scholars, such as Ibn ‘Uthaymin, who holds that it is permissible to gift an unknown item because no harm results from it.