وَفِي بُضْع

In a man’s sexual intercourse with his wife, there is a Charity (for them both).

How can this be a charity?

To satisfy your sexual passion is not a sin.  If a man were to do something forbidden such as fornicate, this would be a sin on his part?

On the other hand, mutual sexual satisfaction with your wife should be rewarded.

This indicates that permissible actions may become acts of worship if there is a sincere intention.  Intercourse may be an act of worship if the intention behind it is to fulfil the rights of one’s wife, to treat her kindly as enjoined by GOD, to seek a righteous child, to keep oneself or one’s wife chaste, to prevent both partners from looking towards or thinking of bad things, and other good intentions.

Related by Muslim

O Young Men! Whoever among you can afford to get married, let him do so, for it is most effective in lowering the gaze and protecting the chastity. And whoever cannot get married, then let him fast, for it will be a protection for him.

“For Muslim men and women― for ‘believing men and women,’ for devout men and women, for true men and women, for men and women who are patient and constant, for men and women who humble themselves, for men and women who give in charity, for men and women who fast (and deny themselves) for men and women who guard their chastity and for men and women who engage much in Allah’s praise― for them has Allah prepared forgiveness and great reward;” Quran 33:35.