What is the ruling on money found in a house that was purchased after its owners' death?

If the treasure was deposited by the homeowner and forgotten by him, then it belongs to him and his heirs, because it is not an appurtenance of the house. However, if it was buried in the ground, it falls into two categories: 1. If it is from the burials of the Jahiliyyah (pre-Islamic era) (bearing their signs and marks), then it belongs to the one who finds it, according to the more preponderant opinion. 2. If it is from the burials of the people of Islam (bearing an Islamic sign, or the name of the Prophet, or a Quranic verse), then it is a found item (luqatah). It must be publicized for a year, and if its owner or heir is found, then they have a greater right to it. Otherwise, the one who found it may benefit from it, while the owner's right remains.

If it is recent and it appears that the seller of the house was the one who buried it and forgot it, then the treasure belongs to him and should be given to his heirs.