Is the wife considered sinful for taking maintenance from her husband according to Indian law, and what is the husband's reward in Islam if he pays it, knowing that she takes a third of his income without a legitimate religious reason?

Firstly: If the divorce is revocable, then the husband is only obligated to provide for his wife during her waiting period (iddah), and he is not required to spend on her for a full year.

Secondly: A Muslim must seek judgment according to the Qur'an and Sunnah, and it is not permissible for him to seek judgment according to man-made laws except out of necessity. If the court rules in his favor for more than what is rightfully his, he is not permitted to take the excess, for it is a piece of fire.

If the wife refuses to seek judgment according to Islamic Sharia, and the husband is compelled to resort to man-made laws, then any money the wife takes wrongfully from him is considered an injustice. If she does not return the right in this world, then the reckoning will be in terms of good deeds and evil deeds on the Day of Resurrection.