What is the ruling on selling a car through a broker who requested that its defects not be mentioned and taking the remaining price, and am I sinful for not knowing its defects and the existence of malfunctions in the cars I bought later?

The seller must disclose the defect in the merchandise if he knows it, otherwise he is a deceiver. Disclosing the defect is among the causes of blessing in the sale. The seller's statement: "Examine the car" is not sufficient as long as he knows the defect. Selling with disavowal of defects is permissible if the seller does not know of the defect.

If the seller knows of the defect and does not disclose it, he must repent, seek absolution from the buyer, and give him compensation for the defect if he wants it; otherwise, he should give it in charity on his behalf. The compensation for the defect is the difference between the value of the car with the defect and its value when sound, taken from the price.