If the money came from your professional life, you need to prove it was already taxed or fell under the taxable limit.
Bank Statements: At least the last 12–24 months of statements showing the gradual accumulation of funds.
Salary Slips & Tax Returns: Copies of your filed Income Tax Returns (ITR) and Wealth Statements for the previous years. The "Wealth Statement" is crucial because it should ideally already show these savings.
Tax Certificates: Form 149 (for salaried individuals) or evidence of withholding tax paid on other income.