What are the duties of the son-in-law in Islam? I did plenty of research and I kept coming up with articles about Mother-Son and Wife issues; the Oedipus complex. I was more interested in a different combination; Mother-Daughter and Husband.
Truthfully, I couldn't find anything with a good substance or scripture. Disappointed, I reflected on the few good men of my biological family since I grew up around them. And alhamdullilah, I came up with a list of things they strove to make their duties.
1. They respected their wives
The few good men knew the women they married were valued in the eyes of their respective families. So they took heed and put these women in their lives on a pedestal. What father doesn't see his daughter as special or any man unworthy of his true gem? Many if not all! Fathers are reluctant about their sons-in-law but realize somehow, somewhere, that they were once scrutinized by their in-laws and they back down some. Some but not completely.
2. They were generous
The few good men always helped their in-laws when they needed money or any other service. Even if the few good men didn't have it, they strove to help any way they could. Over the years, I have heard some men say to their wives, "I'm not obligated to help your family." Sure, perhaps they aren't obliged to help but it shows good manners and courtesy when a son-in-law makes it his duty to be generous to his in-laws. The in-laws will pray for him. And duas and the after-life can't be bought!
3. They inspired leadership
The few good men knew how to lead their families (theirs, their wives', and their nuclear one). When their names are mentioned, you could see the awe and respect in the family members' eyes. They were proud of their sons.
4. They respected their elders and in-laws
The few good men never trampled all over customs and traditions just because they made more money than the rest of the family. Their status never got to their heads. They observed to the letter the way to receive in-laws and how to send them off after their stay; usually with PLENTY of fare money. Now, not every son-in-law has pockets full of cash. But, if they can't support their in-laws financially, they strove to put their in-laws on a high and respected pedestal above the wives they had married. To finish here, the few good men never felt like their family name or history entitled them to a tribal superiority.
5. They made an effort to know the extended family
The few good men knew their respective families and the family they married into very well!
With mahram rules as a curve ball, this can be challenging. However, it doesn't hurt to inquire on non-mahram every now and then so that you can show that you care. And if your mother-in-law remarried, strive to know her new husband. It says that you care and that you were raised right. If language is a barrier, ask your wife to act as a translator. It's actually quite easy because I've done this plenty. It's so embarrassing when you don't know who married who or what in your family because mahram rules are so far your hmm. *Forgive my French.*
A man who doesn't know his own family will probably never know his wife's family well. It's that simple. Of course we should live like Al-Goraba but we should condemn poor social skills. Islam is a religion of peace that encourages good manners and neighborliness. Also, don't make assumptions about your in-laws if you barely know them. They could be better Muslim than you.
Why is it that when it comes to good manners that Islam dictates, a well-mannered son-in-law is suddenly not 'required'? I get it, a good wife doesn't distribute the belongings of her husband to her family and so forth. I doubt the Sunnah says to men 'Close your door to your in-laws, they are not your responsibility. They should stay at a hotel. etc.'
That's where I say "Etre de mauvaise foi." Why? Because family cultures are suddenly seen as un-Islamic when they have nothing to do with Islam really. It's about common courtesy instead.
Above all, many men need to get rid of that 'I have no duties toward your family' mentality. It's selfish, totalitarian, and plain ole dictator'ish' .