What is the ruling on one who swears to avoid his wife for more than four months or less for trivial reasons, and is he sinful for his oath, and was the Prophet's oath regarding his wives for a valid reason?

It is not permissible for a husband to swear an oath to abstain from conjugal relations with his wife for more than four months, because he has sworn an oath to abandon a duty, and this is not part of living together honorably. It is permissible for a man to swear an oath to his wife for less than four months if there is a valid reason, such as disciplining the wife, in accordance with the saying of Allah the Almighty: ﴿As for those [wives] from whom you fear defiance, admonish them, and abandon them in bed, and strike them. But if they obey you, do not seek a way against them. Indeed, Allah is ever Exalted and Grand.﴾ Iyla’ is the oath to abandon sexual intercourse with one's wife for more than four months. Allah the Almighty has set a limit of four months for the one who takes such an oath. If this period expires, the ruler demands that he either return to his wife and expiate his oath, or divorce her, as Allah the Almighty says: ﴿For those who swear to abstain from their wives is a waiting period of four months. And if they return [to their wives], then indeed, Allah is Forgiving and Merciful. But if they resolve on divorce, then indeed, Allah is Hearing and Knowing.﴾ The revelation affirmed the Prophet’s (peace be upon him) iyla’ from his wives for one month, which indicates that what he did was an act of wisdom. This was for disciplining them due to the divulging of a secret or demanding an increase in maintenance.