What is the ruling on profits gained from dealing with an usurious company, while being unaware of its usurious nature, then ceasing to deal with it immediately upon gaining knowledge?

If one has dealt with an usurious company unknowingly, and then comes to know, he must dispose of the ill-gotten money. If the company has a permissible activity, then he should only give away the amount of forbidden usury. But if it engages solely in usurious activity, then he must dispose of all the money by spending it on the welfare of Muslims, along with sincere repentance; for seeking knowledge is an obligation upon every Muslim.