What is the ruling on continuing to publish advertisements for selling cars that the father describes inaccurately and whose defects he conceals, and does the sin fall upon the son who publishes the advertisements or upon the father alone?

The seller must refrain from deception, which is describing a product with qualities it does not possess or concealing its defects. Deception is a major sin, as the Prophet, peace and blessings be upon him, said: "Whoever deceives is not from me."

You are not permitted to assist your father in deceiving customers when selling cars. Rather, confine yourself to mentioning truthful descriptions. If he insists on lying, then refrain from advertising altogether and explain to him the impermissibility of deception and assisting in it. The seller must disclose any defects in the product, and it is not sufficient to say "inspect the car" if he knows of a defect in it.

The greatest advice you can offer your father is regarding prayer, for abandoning it is an act of disbelief. Likewise, advise him to observe the fast of Ramadan, for breaking even one day of it without a valid excuse is a grave sin.