What are the Islamic legal rulings for dealing with an older wife? Is she obligated to obey him completely, just like a younger wife? And should she be given special respect for her age?

The principle governing interaction with one's wife is "kindly companionship," as Allah commanded in His words: "And live with them in kindness." This applies to all wives, regardless of their age, and a wife's obedience to her husband is also obligatory. Nevertheless, Islamic law requires the younger to respect the elder, for the Prophet, peace and blessings be upon him, said: "He is not of us who does not have mercy on our young and does not respect our elders." A wife's observance of her husband's rights and a younger husband's observance of the right of seniority preserve affection and perpetuate companionship.