X' on 1^st July, 2018 agrees to sell his house to 'Y' for a price of Rs. 1 crore, if the entire price is paid on or before 31^st July, 2018 and for the price of Rs. 1,25,00,000/- after 31^st July, 2018 but before 30^th September, 2018. It was further agreed that if the entire price is not paid by 30^th September, 2018, 'Y' shall not be entitled to purchase the house and the earnest money paid by 'Y' to 'X' shall stand forfeited. Such an agreement: