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.
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.