Is it permissible to amend a sales contract that includes a penalty clause and a non-amendment clause, especially with the possibilities that the contract was not read, or the non-amendment clause was forgotten, or its existence was not believed, particularly since the questioner was not praying at the time of signing the contract? What is the ruling on this for those who consider one who abandons prayer to be a disbeliever or not a disbeliever? Does the questioner have the right to revoke the sale of his share in the shop to his brother in exchange for the penalty clause, or has the shop already entered into the brother's ownership?

Your religious status does not affect the validity of the sales contract. Contracts are valid and binding if they meet their conditions. If an agreement was made with your brother for the sale and he accepted, and then you parted ways, the sale is binding, and you cannot retract it except with his consent. The penalty clause is valid and binding in financial contracts other than debts. You are not allowed to amend the contract or its conditions without your brother's approval. If he refuses, you must either proceed with the contract as is or annul it and abide by the penalty clause, unless the penalty clause is excessive, in which case it should be adjusted justly and equitably. We advise you to reach an understanding with your brother and uphold the ties of kinship.