it return 3 for business

Usually, Financial statements of the business with P&L acc & BS. TDS certificate &/or Form 26AS. tax audit reports, if applicable etc. etc.

ITR-3 is the ITR Form to report business income. No documents are required to be attached while filing ITR-3 on the income tax website. Here is a list of required documents to prepare ITR-3. 

1. PAN
2. Aadhar
3. Bank Statements of the financial year (1st April to 31st March)
4. Income related documents - Form 16 for Salary Income, Interest Statement, Rent Receipts, Capital Gains Statement, Trading Statement, etc
5. Form 26AS - You can download it from your account on the income tax website
6. Deduction Proofs - Loan Statement, LIC Receipts, Mediclaim Receipts, PPF Investment, ELSS Statement, etc