It must be stamped, and all units that follow the rules require the other party to issue a receipt. Because if you make a payment through a bank, you can have a bank voucher, but there is no voucher for payment and acceptance, so you need a receipt to do the accounting. To prove that the money has been paid to you. (If you’re worried about getting a stamp, just engrave it yourself. It doesn’t matter if you get the receipt, no one will check it.

)