Is the signature of a son on behalf of his blind father on a land sale contract, without a legal power of attorney, binding on the father to complete the sale, especially after he regained his sight and refused the sale, knowing that the buyer did not meet the father?

If the father's land is sold by his son without his authorization, the sale is invalid because it is a disposition of another's property without permission, and it is not permissible to sell what you do not own. Therefore, the father has the right to refuse to complete the sale as long as he did not authorize it.