What is the ruling on killing a scorpion, grinding it, and feeding it to an infant before weaning so that their body becomes accustomed to it and is not affected if stung when older?

The scorpion is an insect. It is not permissible to eat insects according to the Hanafis, Shafi'is, and Hanbalis, and this is the most preponderant opinion, because insects are considered detestable (khaba'ith). Allah Almighty says: "And He makes unlawful for them all evil things" (Quran 7:157). Furthermore, there is a command to kill scorpions and they are referred to as "fawasiq" (noxious creatures). Therefore, feeding a scorpion to a child or anyone else is forbidden (haram).