If he gets married with a dowry, part of which is deferred until the time of death or separation
Question

If someone gets married with a dowry, some of which is to be paid immediately and some of which – according to local custom – is deferred until the time of death or separation, is that valid?
Praise be to Allah.This deferral is valid, whether they state it explicitly or that is in accordance with  their established custom.
Based on that, neither the woman nor her  family has any right to demand the deferred portion when she is still married to him, and she has no right to refuse to go back to him until she receives the deferred portion, because they agreed at the time of the marriage contract to delay it in the manner mentioned above. If she goes to her family and they say: We will not let her return until the husband pays what remains of the dowry, they have no right to do that, and their refusal to let her go back is wrong and has no justification. If she persists in refusing to go back to him on these grounds only, she has no right to maintenance from the husband, because she is showing defiant disobedience, and the woman who shows defiant disobedience has no right to maintenance. End quote.
Shaykh ‘Abd ar-Rahman ibn Nasir as-Sa‘di (may Allah have mercy on him).
Al-Fatawa as-Sa‘diyyah (502).