What is the ruling on taking money, the permissibility of which is doubted—money that the mother claimed was permissible for selling land without a deed, which no one objected to, despite the questioner hearing that it must be sold without the relatives' knowledge—and what is the ruling on using a phone bought with this money?

As long as you know that this land was in your mother's possession since you were young, and then it was offered for sale to the public and no one claimed it, then it is considered your mother's property. This is because her long-term possession of it and the absence of any claimant indicate that it belongs to her.

Ibn Asim al-Maliki said in Tuhfat al-Hukkam: "If a stranger possesses a property with right For ten years, ownership is then his entitlement. And the claimant's argument is nullified, Even with his presence, from disputing it."

So, if a person comes after this period and after the announcement of the land's sale, claiming ownership, his claim will not be heard, unless he claims that he rented this land for your mother or something similar, and he must prove this with valid Sharia (definition) evidence; otherwise, his claim will not be heard at all. And as long as you can find a legitimate way out for your mother and your brother, it is not permissible for you to boycott them merely based on doubts or delusions that are not supported by legitimate Sharia evidence.