Offering the funeral prayer over the grave when visiting it
Question

                Is it permissible for me to offer the funeral prayer over my father's grave when visiting it, seeking mercy for him? If the deceased bequeathed a Mushaf, will he get reward when his children read it?.
Praise be to Allah.
      If you already offered the funeral prayer for your father 
      with the people, there is no need to repeat the prayer; rather you should 
      visit his grave and offer supplication for him only; you should go to the 
      graveyard and greet the occupants of the graves with salaam, and offer 
      supplication for them and for your father, as the Prophet (blessings and 
      peace of Allah be upon him) said: “Visit the graves, for they will remind 
      you of the Hereafter.” 

    The Prophet (blessings and peace of Allah be upon him) used 
    to teach his Companions, when they visited graves, to say: Al-salaamu 
    ‘alaykum ahl il-diyaar min al- Muslimeen wa’l-mu’mineen, wa innaa in sha 
    Allaah bikum laahiqoon, yarham Allaah al-mustaqdimeena minna 
    wa’l-musta’khireen, nas’al Allaah lana wa lakum al-‘aafiyah (Peace be 
    upon you, O occupants of the graves, Muslims and believers. Verily we will, 
    in sha Allaah, join you. May Allaah have mercy upon those who have gone 
    ahead of us and those who will come later on. We ask Allaah for well-being 
    for us and for you).” This is the Sunnah. 

    So you may greet the occupants of the graves and your father, 
    and pray (du‘aa’) for forgiveness and mercy for him; there is no need to 
    offer the funeral prayer. This applies if you did offer the funeral prayer 
    for him. 

    But if you did not offer the funeral prayer for him with the 
    people, you may go to his grave and offer the funeral prayer for him within 
    one month or less, if it is one month or less since he died. But if a long 
    time has passed, one should not offer the funeral prayer, according to a 
    number of scholars. Supplication (du‘aa’), praying for forgiveness for your 
    father, asking for mercy for him and giving charity on his behalf are all 
    acts that will benefit the deceased, whether he is a father or anyone else. 

    With regard to the Mushaf that the deceased left behind, it 
    will benefit him if he left it as a waqf (endowment), as the reward for it 
    will benefit him. Similarly if he gave as a waqf books of beneficial 
    knowledge, Islamic knowledge or any permissible branch of knowledge or 
    science from which the people can benefit, he would be rewarded for that, 
    because it is helping in something good. Another example is if he left some 
    land or a house or a shop as a waqf, for charity to be given to the poor or 
    donated to the mosque by its income. For all of these things he would be 
    rewarded. The Prophet (blessings and peace of Allah be upon him) said 
    according to the saheeh hadeeth: “When a man dies, all his good deeds come 
    to an end except three: ongoing charity, beneficial knowledge, and a 
    righteous son who will pray for him.”  

    Ongoing charity will benefit the deceased if he was a Muslim, 
    and he will also be benefited by the supplication of his children and 
    others, and by the waqf that he set up for charitable purposes such as a 
    house, land, a shop, date palms and so on. He will benefit from this waqf if 
    people benefit from it, if they eat from its income and benefit from its 
    income, or its income is spent on maintaining and furnishing mosques for the 
    Muslims. End quote. 

    Shaykh ‘Abd al-‘Azeez ibn Baaz (may Allah have mercy on him).