All praise is due to Allah, and peace and blessings be upon our master, the Messenger of Allah ﷺ.

Islam has prohibited every act that leads to what is unlawful. Allah, the Exalted, says {what means}: "And do not assist one another in sin and transgression" [al-Mā'idah/2]. And on the authority of Jābir (raḍiyallāhu ‘anh), he said: " God's Messenger cursed the one who accepted usury, the one who paid it, the one who recorded it, and the two witnesses to it, saying they were all alike. " (Related by Muslim)

The actions a Muslim undertakes are divided, based on their original ruling and based on what they may lead to or serve as a means toward, into the following categories:

1. Acts unlawful in themselves, regarding whose prohibition there is no disagreement among the scholars — such as drinking wine, entering into a ribā-based contract, and the like. These remain unlawful even if their ultimate purpose is permissible, because a permissible end does not make unlawful means permissible.

2. Permissible acts free of any doubtful element — namely, anything the Sharī‘ah has not prohibited, such as buying, selling, partnership, and other matters whose prohibition has not been established. These are lawful.

3. Acts permissible in their basic nature, but which serve as a means to reach something unlawful, or which function as a means toward it. These are further divided, in terms of their being a means leading to something unlawful, into the following sub-categories:

• A prohibited category: This includes whatever definitively leads to something unlawful, or leads to it according to overwhelming probability (aẓ-ẓann al-ghālib). This encompasses whatever constitutes a pillar (rukn) of the unlawful contract, a direct cause (sabab) of it, a condition (sharṭ) within it, or a means of documenting and establishing (tawthīq) it.

• A permissible category: This includes whatever is connected to the unlawful contract but does not fall under the previous category — such as cases where there is merely doubt as to whether it leads to something unlawful. Such cases remain governed by the original ruling of permissibility — though the value of scrupulousness (wara‘) in avoiding them is not hidden — and a Muslim is not obligated to investigate the ultimate purpose behind every individual customer's purchase.

Accordingly, working at conventional (commercial) banks and ribā-based financial institutions is divided into two categories:

A prohibited category: This is whatever the ribā-based transaction cannot be completed without, and upon which its existence depends. Everything that serves as a means to something unlawful takes the same ruling as that unlawful matter itself, since means take on the ruling of their ends (al-wasā'il ta'khudhu ḥukm al-maqāṣid). This encompasses every position and function upon which the completion, execution, documentation, or administration of the ribā-based transaction depends.

A category that is not unlawful, though scrupulousness dictates avoiding it: This encompasses positions and functions upon which the completion, execution, documentation, or administration of the ribā-based transaction does not depend. We hope that no sin is incurred by engaging in such roles, since the evidence establishing prohibition does not extend to them as it does to the prohibited categories mentioned above. However, such roles are not free of being disliked (karāhah), and it is preferable to avoid them. The Messenger of Allah ﷺ said: "The lawful is clear, and the unlawful is clear, and between the two are doubtful matters (mushtabihāt) that many people do not know [whether they belong] to the lawful or the unlawful. Whoever avoids them safeguards his religion and his honor, and whoever falls into doubtful matters is at risk of falling into the unlawful." (Related by at-Tirmidhī, who said: "This is a ḥasan ṣaḥīḥ ḥadīth.")

Imam ar-Ramlī ash-Shāfi‘ī (raḥimahullāh) said — regarding the prohibition of selling items such as fresh dates or grapes to someone who will press them into wine: "The evidence for this is his ﷺ cursing, with regard to wine, ten [parties involved in it], including the one who presses it and the one for whom it is pressed — the ḥadīth indicating the prohibition of any act that causes, or assists in, sin. And the attribution to the majority [of scholars] of a ruling of permissibility here [i.e., alongside disapproval/karāhah] is to be understood as applying to cases where there is [merely] doubt as to whether he intends to press it [into wine]." [Nihāyat al-Muḥtāj, Vol.3/P.471]

As for someone who assists ribā-based banks without being formally employed by them, the ruling in his case differs according to the degree of assistance ('i‘ānah) involved. Whoever assists in what is unlawful, serving as a means toward it, his assistance is unlawful — such as opening an interest-free current account at a ribā-based bank without any recognized need, since in reality this constitutes lending funds to the bank, which will then use this money to engage in ribā-based dealings with others. Similarly, leasing a building to a bank that will use it as a center for its ribā-based operations constitutes unlawful assistance.

As for whatever does not serve as a means to the unlawful act — such as selling "cybersecurity" services, meaning the protection of funds and information from theft and attack — such assistance does not reach the level of prohibition, and is permissible.

As for the employee who works in a role involving assistance in something unlawful: if leaving his job would result in ruin (tahlukah) for himself, or the loss of livelihood for his dependents, then this is a matter that is tolerated (yutasāmaḥ bihi) out of necessity (ḍarūrah). He may continue in his job, taking only what covers his need, and disposing of the remainder [of impermissible earnings], until he finds another position — while remaining obligated to search for alternative work, even if it comes with fewer benefits — in accordance with the Sharia maxim: "Necessities render prohibited matters permissible" (aḍ-ḍarūrāt tubīḥ al-maḥẓūrāt), and "Necessity is estimated according to its true extent" (aḍ-ḍarūrah tuqaddar bi-qadarihā).

In conclusion: it is unlawful to work in positions upon which the completion, documentation, execution, or administration of the ribā-based transaction depends. As for positions that have no connection whatsoever to the ribā-based transaction, as detailed above, their ruling is one of disapproval (karāhah), and it is preferable to avoid them. As for someone who is not among the bank's employees, the ruling regarding his work differs according to the degree of his assistance in what is unlawful, and its connection to it, as explained above.

This is the general breakdown, and the employee himself is best positioned to accurately describe the nature of his own work. We remind [the reader] of the words of Allah, the Mighty and Majestic {which mean}: "And whoever fears Allah — He will make for him a way out, and will provide for him from where he does not expect. And whoever relies upon Allah — then He is sufficient for him" [Sūrat aṭ-Ṭalāq/2–3], and that whoever leaves something for the sake of Allah, Allah will compensate him with something better than it. And Allah, the Exalted, knows best.