What is the ruling on someone who found a small amount of money and took it after its owner inquired about it, but he does not know the owner or their location, and then the money was also lost from him? And is he obliged to return it if its owner comes to him a second time?

If a person picks up a lost item intending to return it to its owner, and he cannot find the owner, and the item is lost from him without negligence or dereliction, then he is not liable for it because he is a trustee. However, if he took it intending to benefit from it, or if his negligence in preserving it is proven, then he is liable for it, because neglect of trusts necessitates liability. It is forbidden for someone who does not feel secure about himself concerning a lost item to take it, and he is liable for it if it perishes absolutely, because he took someone else's property in an impermissible manner.