Is it permissible to work in preparing and amending the formulas for documentary credits, and is the documentary credit, with its mentioned stages of payment, considered permissible (halal)?

The ruling on a letter of credit varies depending on its nature. If it is fully covered by the applicant, it is considered an agency, and it is permissible to charge a known fee for it. However, if it is not covered, it is considered a loan, and any excess amount taken by the bank is considered usury (riba). Accordingly, if the letters of credit are of the first type, there is no harm in opening them. But if they are of the second type, it is not permissible due to its involvement in cooperating in sin and aggression, validating usury, and bearing witness to it, based on the Almighty's saying: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression" (Quran 5:2). And based on the Prophet's (peace be upon him) saying: "The Messenger of Allah (peace be upon him) cursed the one who consumes usury, its giver, its scribe, and its two witnesses, saying: 'They are all equal (in sin).'"