What is the ruling on selling dollars with an ordinary, uncertified check, whereby the check is handed over by the account holder in exchange for dollars, due to the difficulty of immediate cash exchange at the bank?

For currency exchange, it is a condition that possession takes place before separation. A certified check is considered constructive possession, while an ordinary check is not; therefore, it is impermissible to exchange it for cash currencies. It is permissible to deal with a bank check, certified check, or their equivalent when exchanging currencies or purchasing gold or silver. As for an ordinary check, it is not permissible to use it in transactions where possession is a condition.