What is the ruling on a husband divorcing his wife three separate times on days of contentment, without having intercourse with her after the first divorce, and is the husband sinful for divorcing her when there are no children?

The gist of the Fatwa: Divorcing one's wife has two scenarios:

The first scenario: If the divorce occurred for the first time and you did not reconcile with her, then you divorced her twice after the 'iddah (waiting period) ended, the first divorce causes a minor irrevocability. The subsequent two divorces are not counted, and you are permitted to renew the marriage contract with her, provided the conditions of marriage are met.

The second scenario: If the second and third divorces occurred during the 'iddah, then they are counted, and the wife becomes irrevocably separated from you with a major irrevocability. She is not permissible for you until she marries another man out of genuine desire, and he divorces her before consummation.

Regarding your question about your mother, it is preferable for you to return to your wife with a new contract if she is permissible for you, as an act of filial piety towards your mother. However, you do not sin by not complying with her command, nor are you considered disobedient to her in this case.

As for sinning by divorcing your wife, divorce falls into five categories, and you only sin if you divorce her in one of the situations where divorce is forbidden.