Selling a car in installments and stipulating receiving the buyer's service

A: In the sale contract you have stipulated another contract; leasing and this completely cancels the contract. The evidence that this contract is null and void is based on what was related by Abu Dawud and Al-Tirmidhy who graded it as good Hadith on the authority of `Abdullah ibn `Umar (may Allah be pleased with them both) that the Prophet (peace be upon him) said: A loan and a sale are not lawful (together), or two conditions in a sale, or to sell what you do not have. Accordingly, you should be careful not to do this in the future. As for the past, we hope that Allah (Exalted be He) will pardon you for your ignorance of the ruling. Allah (Glorified and Exalted be He) says: So whosoever receives an admonition from his Lord and stops eating Ribâ (usury) shall not be punished for the past; his case is for Allâh (to judge) May Allah grant us success. May peace and blessings be upon our Prophet Muhammad, his family, and Companions.