What is the ruling on the letter of guarantee that a merchant requests from the bank in exchange for a commission, for importing goods?

A letter of guarantee (bank guarantee) is either covered (backed by collateral) or uncovered. If covered, the relationship between the applicant and the issuer is one of agency (wakalah). If uncovered, it is a guarantee (dhaman) or suretyship (kafalah). Jurists have ruled that it is impermissible to take a fee for a suretyship because it is a gratuitous contract intended for benevolence and kindness. Accordingly, it is impermissible to take a fee for a letter of guarantee, whether covered or uncovered. However, administrative expenses for issuing the letter of guarantee are permissible according to Sharia, provided they do not exceed the customary fee (ajr al-mithl).