What is the ruling on a deceased person's will for his son to marry his paternal or maternal cousin, despite the son's unwillingness, and what is the ruling on the mother's insistence on that?

The son is not obligated to carry out his father's will to marry a specific woman whom he does not desire, nor is he bound to comply with his mother's insistence on that; for neither parent has the right to compel their child to marry someone they do not wish, and if he refuses, he is not considered disobedient. Marriage is a momentous contract and a solemn covenant, and it endures for life.