Should he do the obligatory Hajj or use the money to get his son married?
Question

                If there is a man who wants to do the obligatory Hajj (i.e., Hajj for the first time) and he has a son who is single and of marriageable age, and this man has only enough money either to do Hajj or to get his son married, in this case which takes precedence? Should he do the obligatory Hajj or get his son married?.
Praise be to Allah.Firstly: 
A man has to 
    get his son married if the son needs to get married and cannot afford to do 
    so by himself, according to the more correct of the two scholarly opinions, 
    because the need for marriage may be no less than the need for food and 
    drink, so it comes under the heading of obligatory spending. 
Al-Mardaawi 
    said in al-Insaaf (9/204): A man is obliged to keep chaste those on 
    whom he is obliged to spend, namely fathers, grandfathers, sons, grandsons 
    and others on whom he is obliged to spend. This is the correct view in the 
    madhhab of Imam Ahmad. End quote. 
Shaykh Ibn 
    ‘Uthaymeen (may Allaah have mercy on him) said: A person’s need for marriage 
    is urgent and in some cases may be like the need for food and drink. Hence 
    the scholars said that it is obligatory for the one who is obliged to spend 
    on a person to arrange his marriage if he can afford that. So the father has 
    to get his son married if the son needs to get married and cannot afford it. 
    But I have heard about some fathers who forget how they were when they were 
    young, when their sons ask them to help them get married, they say, Get 
    married at your own expense. This is not permissible and it is haraam if he 
    can afford to get him married. His son will dispute with him on the Day of 
    Resurrection if he did not get him married when he was able to do so. 
Secondly: 
If there is 
    a conflict between the father’s Hajj and the son’s getting married, because 
    the father only has enough money for one of them, then he should look to see 
    whether his son’s marriage is essential right now, or can it be delayed? If 
    the son needs to get married and fears that he may do something haraam, then 
    getting him married takes precedence over the father’s doing Hajj. It takes 
    precedence over the father’s Hajj for two reasons:  
1 –Keeping 
    him chaste and protecting him against doing haraam things is obligatory and 
    cannot be delayed, whereas Hajj may be delayed until Allaah makes it 
    easier. 
2 –Hajj is 
    not obligatory for the father unless he has money that is surplus to what he 
    needs to spend for his own expenses and those of the people on whom he is 
    obliged to spend. In this case he is obliged to get his son married so that 
    he will not do something haraam. 
Ibn Qudaamah 
    (may Allaah have mercy on him) said in al-Mughni (5/12): If he needs 
    to get married and fears hardship for himself, then getting married takes 
    precedence over Hajj, because it is obligatory for him and he cannot do 
    without it, so it is like spending on his maintenance. But if he has no such 
    fear, then Hajj takes precedence, because marriage is voluntary and should 
    not take precedence over the obligatory Hajj. End quote. 
See also: 
    al-Majmoo’ (7/71) by al-Nawawi, and question no.
    27120. 
But if the 
    son does not need to get married or he does not fear that he may do haraam 
    things if he delays marriage, then he does not have to get him married now, 
    and in this case Hajj is obligatory for the father, because he has money 
    that is surplus to what he needs for his own expenses and those of the 
    people on whom he is obliged to spend. Allaah says (interpretation of the 
    meaning): 
“And Hajj 
    (pilgrimage to Makkah) to the House (Ka‘bah) is a duty that mankind owes to 
    Allaah, those who can afford the expenses (for one’s conveyance, provision 
    and residence); and whoever disbelieves [i.e. denies Hajj (pilgrimage to 
    Makkah), then he is a disbeliever of Allaah], then Allaah stands not in need 
    of any of the ‘Aalameen (mankind, jinn and all that exists)”
    [Aal ‘Imraan 3:97]
And Allaah 
    knows best.