What is the ruling on working in Conventional Banks and depositing money in them without taking interest on the money?
There is no doubt that it is impermissible to work in conventional banks that deal in Riba (usury), as it entails cooperation with them in sin and transgression. Allah (Glorified be He) states,
“And cooperate in righteousness and piety, but do not cooperate in sin and aggression. And fear Allah ; indeed, Allah is severe in penalty.” [Al-Quran, Surah Al-Ma’idah, verse 2].
It is authentically reported that the Prophet (peace be upon him) cursed the one who accepts Riba, the one who gives it, those who witness it, and the one who writes it. He (peace be upon him) said, “They are all equal.” [Related by Muslim in his Sahih (authentic) Book of Hadith].
As for depositing money in banks in return for monthly or annual interest, it is prohibited Riba according to Ijma’ (consensus of scholars).
As for depositing money without interest in a bank that deals in Riba, it is better not to do so, except in case of necessity, because this entails helping them in usurious transactions. Thus, an account owner may be helping in sin and transgression, even if they do not mean it.
We should beware of what Allah prohibited and seek the straight ways to keep the money.
May Allah guide the Muslims to what brings them happiness, honor, and security. May Allah help them establish Islamic banks that do not deal in Riba. He is the One Capable of doing so.
May Allah’s Peace and Blessings be upon our Prophet Muhammad, his family, and Companions.
Sources: Fatwas of Ibn Baz