First of all, we need to tell that violating one of God’s commands deliberately can take you to the limits of kufr, which means ignoring God’s verses, if you do it repeatedly. So, if the situation that you mentioned was not experienced already, you must give up on the idea of consuming that haraam money. You cannot keep on the right way while you consume haraam money. Abu Huraira reported Allah’s Messenger (ﷺ) as saying:
If it already happened and you consumed the haraam money as you also started your business, here is what you should do:
If a person who obtained something through a forbidden way regrets it, wants to repent and get hold of this burden, he must do three things:
Open his heart to God and express his sincere regrets; ask for forgiveness from God; dispose of the haraam money or property by returning it to its owner or the holder of the right.
Disposing of the Haraam Property
If the person also violated another person’s rightful due, or obtained a property through haraam ways, such as theft, seizure, deception, usuriousness, gambling, etc. while committing a forbidden act, then he needs to get that property out of his ownership. If the haraam property is something specific, it is simple to dispose of. A person who seized an animal or a certain article can easily separate it from his wealth and return to its owner if he did not consume it. When the owner is not known, it can be used for charity purposes without expecting God to grant you the merits of charity. For other cases, probabilities are listed below:
1- Two possibilities exist if lawful (halal) items are mixed with unlawful (haraam) items and they are of a type which can be paid back by returning its equivalent (such as grain, money, oil, etc.):
a) The amount of unlawful article is known. Then, that amount of property (grain, oil, money, etc.) is separated and removed out of the wealth.
b) The amount of unlawful article is not certain. In that case, the prevailing assumption is considered. The amount of article which is highly possible to be unlawful is removed. The way of piety is keeping the amount which is certainly known to be lawful and removing the rest.
2- If the unlawful (haraam) items which were mixed with lawful (halal) items are of a type which may have distinct values, such as house, field, etc., what to do is seeking reconciliation and asking for the blessing of the real owner of the properties. The main principle is “returning the property as is” to the holder of the right. If this is not possible, equivalent of that item is to be given. If this is also not possible, a payment equivalent of the worth of the property is made. Then, you can ask for the blessing of the right-holder.
If the right-holder is deceased, you can make the payment to his/her heirs.
In both cases, if that haraam money or property constitutes a huge amount which is not possible to remove out of your wealth at once, you must do it step by step, but as soon as possible.