On 1st April 2020, Khatijah bought a car from Othman for RM20000 to be paid in two instalments of RM10000. Khatijah did not pay the second instalment when it was due. Othman felt sorry for Khatijah, who lost her job not long after buying his car due to current economic and pandemic crisis. He told her that if she paid him the half of what she owed him RM5000 by the 1st week of June 2020, he would let her off with the rest. Khatijah paid him RM5000 on 6th June 2020. On 10th June 2020, Khatijah was notified that she had been successful in one of her job applications and would be starting work on the 1st July 2020 at a much better salary than her old job. Othman heard about Khatijah's new job and realized that she had no financial difficulties anymore. He now wished to claim the rest of the money which she had originally agreed to pay for the car.

By virtue of Malaysian Contracts Act 1950 and decided case laws, discuss all the contractual issues in the above case. Discuss also the position of Islamic Law relating to the above issues