Addressing this issue,, Dr. `Abdel-Fattah Idrees, Professor of Comparative Jurisprudence, says:
‘Spending on the mother is a duty upon the children who are able to earn living or have money when the mother has no money to spend and is not able to earn her living. But this does not prevent the adult child from marrying, for Almighty Allah said: “Let the man of means spend according to his means: and the man whose resources are restricted, let him spend according to what Allah has given him. Allah puts no burden on any person beyond what He has given him. After a difficulty, Allah will soon grant relief” [al-Talaq 65:7]
This means that whoever is obligated to spend on his mother and his resources are restricted or is partially unable to spend on his mother if he gets married, then let him spend out of what Allah has granted him. Thus, he is not absolved of spending on his mother as long as he is able to work and he should do so according to his resources; because such spending is a Sharia obligation and Sharia obligations are conditioned by the ability and capability of the responsible Muslim.
Accordingly, neither marrying should prevent such a person from spending on his mother nor spending on his mother should prevent him from preserving his chastity through marriage; especially if he fears of suffering sexual frustration in these days of overwhelming temptations.”