Payment from more than one bank account

If we purchase one asset and payment from more than one bank account, suppose:

Asset of amount 1000 and paid from Bank-A 600 and from Bank-B 400 how can we record this transaction in one payment entry?

Debit: Asset 1000
Credit: Bank-A 600
Credit: Bank-B 400

You cannot. If two banks are involved, there are two transactions.