Tawarruq
Simply put
The aim of Tawarruq is to obtain liquidity, not the goods themselves. You buy goods (metals, for example) in installments, then sell them for cash to a third party, so cash enters your account and you owe installments larger than it.
In accounting terms it is cash financing: you record the cash received and a liability to the bank, and the difference between the total installments and the cash received is a finance cost spread over the repayment period. You do not record the goods as inventory, because they left immediately.
Worked example
A pharmacy needs liquidity to buy stock for the season, so it bought metals from the bank at a deferred price of 108,000 SAR payable within a year, then immediately sold them to another party for 100,000 SAR in cash.
Formula: Tawarruq cost = deferred price − cash received from selling the goods