Praise be to Allah.
What the one who disobeys Allaah and commits major sins must do is hasten to repent, and beware of procrastinating and delaying, for perhaps death may come upon him and the door of repentance will be closed to him, and he will be lost, as Allaah says (interpretation of the meaning):
“And of no effect is the repentance of those who continue to do evil deeds until death faces one of them and he says: ‘Now I repent’; nor of those who die while they are disbelievers. For them We have prepared a painful torment”
What is keeping him from repenting? Why is he persisting in sin and hesitating, when the Lord of the Worlds is holding out His hand at night to accept the repentance of the one who sinned during the day, and He is holding out His hand during the day to accept the repentance of the one who sinned during the night, and He rejoices over the repentance of His slave and accepts it from him and rewards him for that?
Is it appropriate for the sinner to turn away and persist in his sin, when his Lord is holding out His hand?
Is it appropriate for the sinner to say, “O Lord, O Lord,” and ask for some worldly need, when he is also implicitly saying, “But I am persisting in disobeying You, O Lord”? By Allaah, if we felt shy before Allaah and understood the greatness of Allaah, we would not do that.
As for the fear that the repentance might be because of that worldly matter, this may be waswaas (whispers) from the shaytaan, so that the person will continue in sin and delay repenting.
So what is required is repentance done sincerely for the sake of Allaah, in the hope of attaining His pardon and forgiveness, then the person may ask his Lord for whatever he wants of good in this world and the Hereafter.
Nevertheless we say: If the person persists in his sin, it is not haraam for him to ask of his Lord, even if he is asking for some worldly matter. Allaah may give him what he is asking for, as He is the Most Kind, Most Generous; how kind Allaah is to His slave, despite his shortcomings and negligence. But this attitude is not appropriate for the believer who loves Allaah and venerates Him, and who understand the seriousness of sin and persisting therein. For sins may be a cause of one's being deprived and not having one’s prayers answered.
Hence the Prophet (peace and blessings of Allaah be upon him) mentioned a man who has undertaken a lengthy journey and is disheveled and dusty, raising his hands towards heaven and saying, ‘O Lord, O Lord!’ but his food is haraam, his drink is haraam, his clothing is haraam, he is nourished with haraam so how can he receive a response?” Narrated by Muslim (1015).
We ask Allaah to set our affairs and those of all the Muslims straight.
And Allaah knows best.