What is the ruling on working for a company that has mixed funds (including usurious banks) and whose activity is selling land in installments with interest, and what is the ruling on the money saved from this work?

It is permissible to work for the company if the land sales are in cash or in installments that meet the Sharia conditions and are free from usury. The mixing of the company's money between halal (permissible) and haram (forbidden) does not cause harm, as working for an individual whose wealth is mixed is disliked (makrooh) but not forbidden (haram). Therefore, the money earned from this work is halal. However, if the company sells real estate with usury, then it is not permissible to work for it. As for the money obtained from usurious sales in the past, if it was due to ignorance, it is halal. If it was with knowledge, then it is haram, and it must be given in charity for the public welfare of Muslims.