How can one advise a stubborn husband who is always insistent on being right?

Marital life is a solemn covenant that should be preserved. The goal of both spouses during discussions should be to reach the truth, and they should recall Shu'ayb's saying: "I only desire reform as much as I am able." One should receive the other's opinion with an open mind and gentleness, for the divergence of minds is human nature. If the debater is rigid in opinion, then be gentle and speak kindly, as in His (Allah's) saying: "and speak to people kindly." The wife should advise her husband with good counsel and patience, and repent to Allah for sins, for perhaps what is happening is due to disobedience. After repentance, she should turn to Allah in supplication, and there is no objection to seeking assistance from righteous people for mediation.