Father preventing his son from marrying because he needs his help 
to take care of siblings
Question

                Does a father have any right to prevent his son from getting married on 
the grounds that he needs his help in providing for his brothers and 
sisters?
Praise be to Allah.
If the son will commit haraam acts if he does not get married, then the father has no 
right to prevent him from getting married for the reason stated in the question. Allaah 
is the Provider and those brothers and sisters are part of His creation; He will never 
forsake them. Allaah has promised to help the one who gets married in order to keep 
himself chaste. He says (interpretation of the meaning): 
"And marry those among you who are single (i.e. a man who has no wife and a 
woman who has no husband) and (also marry) the saalihoon (pious, fit and 
capable ones) of your (male) slaves and maid-servants (female slaves). If they be 
poor, Allaah will enrich them out of His Bounty. And Allaah is All-Sufficient for His 
creatures’ needs, All-Knowing (about the state of the people)."
[al-Noor 24:32]
The Messenger of Allaah 
 said: "There are three to whom Allaah’s help is due: the 
mujaahid who goes out to fight for the sake of Allaah; the slaves who makes a 
contract with his master to pay installments towards his freedom; and the one who 
gets married because he wants to remain chaste." (al-Tirmidhi, no. 1566. Abu ‘Eesaa said: this 
is a hasan hadeeth. See also Saheeh al-Jaami’, no. 3050).
But if the son is able to be patient and give himself up to working and helping his 
father to provide for his brothers and sisters, then he will be rewarded, for Allaah 
never allows the reward of those who do good to be lost.
And Allaah knows best.