Is it permissible, Islamically, for a brother to dispose of his movable property, such as land, fearing that his heirs might take it after his death, knowing that he has been married for 30 years and has not had children, and that the infertility is due to him?

It is not permissible to use deception to prevent an heir from receiving their inheritance, as it is a right ordained by Allah the Almighty. A person is permitted to fully dispose of their wealth through gifts, charity, and other means, even if they give away all their money. However, it is preferable not to do so unless one possesses a high degree of contentment, patience, and conviction, as Abu Bakr (may Allah be pleased with him) did. In summary, disposing of wealth is permissible, even if it leads to the depletion of assets, but the intention must not be to deprive the heirs.