TAx Implications towards property advance.

Mr. P, my client, made an advance payment of Rs 604,310 towards a property in the year 2005 to Mr. X and entered into an agreement. However, the agreement never came to fruition. Recently, on 07-01-2023, Mr. X, the property owner, sold the property to another individual, Mr. Y. Interestingly, despite the initial agreement not materializing, Mr. P received Rs. 35,00,000 from Mr. Y as a result of his initial advance payment.

What is the tax implications for Mr. P?