Is the wife whose husband has passed away entitled to claim the deferred dowry from his family?

The deferred Mahr (dowry) is a debt owed by the husband that is not forfeited by his death. The wife has the right to claim it from his estate before it is divided among the heirs, either upon his death or separation. This is what Imam Ahmad stipulated and what Ibn Taymiyyah and others chose. If the husband does not leave an estate, the wife does not have the right to demand anything from the heirs, and it is better for her to waive this debt.