Is it permissible for them to use their father’s money when he does not pray?
Question

                My father, May Allah guide him, does not pray. He does not pray unless he is in a public place or at work, so he does not become embarrassed if people notice that he does not pray. But he does not consider prayers with care. An imam and a congregation from a masjid have advised him to pray, he prayed for a few weeks then stopped. He used to pray Friday prayer before, and now he stopped even praying the jumu’ah prayer. 
 
My question is: Is his money that he spends on us halal or haram? Does the hadeeth of the prophet, peace be upon him that says: “There is no flesh that is nourished by haram things, but the Fire will be more entitled to it.” Apply to us, his children, or not?.
Praise be to Allah.Firstly: 
Not praying is a major sin 
    and cause of doom; in fact it is kufr according to the more correct of the 
    two scholarly opinions, as has been explained in the answer to question no.
    5208 and
    2182. 
The kufr of the one who 
    does not pray leads to numerous rulings in life and after death. Meat 
    slaughtered by him is not halaal, it is not valid for him to be a wali 
    (guardian) or witness in case of marriage, and if he dies he is not to be 
    washed or the prayer offered for him, and he cannot be buried with the 
    Muslims. 
You should carry on calling 
    him, advising him and reminding him, in the hope that he may repent and come 
    back to Islam. See the answer to question no.
    47425. 
Secondly: 
The money that he spends on 
    you is not regarded as haraam or impure, so long as he earns it in a 
    permissible manner, such as a job or trade and the like. What is meant by 
    the hadeeth, “Every body that is nourished on haraam, the Fire is more 
    befitting for it” [narrated by al-Tabaraani and classed as saheeh by 
    al-Albaani in Saheeh al-Jaami’ (4519)] is wealth that is taken in 
    haraam ways such as stealing, deceit and so on. 
We ask Allaah to guide you 
    and give you strength, and to guide your father and enable him to repent. 
And Allaah knows best.