Upon burial, Staying at Grave of Father in Law and reciting for some time?

Assalam o Alaikum! Recently my father in law passed away, and my wife asked me to be at his grave upon burial on her behalf and recite for some time as reflected from posts about the time taken for camel slaughter. I did so because of her will as well as I had a very deep good bond with my father in law. Normally I don't debate over matters I have less knowledge. My friends upon hearing it told me your reciting would not benefit your father in law. I just couldn't accept it as of the basic core of Islam I understand. So I just wanted to ask those with diverse knowledge that being son in law, if I took a part with every single thing in the funeral. Procession and after burying i stayed there for almost 2 hours and recited. Will it benefit my deceased father in law? JazakAllah Regards Nouman Ahmed Khan (40 years, Pakistan)