What is the ruling on a notary's work in authenticating contracts for the sale and mortgage of real estate and equipment acquired through an interest-based loan? Is his earning considered unlawful, and what advice should be given to him?

If the notary writes usurious contracts, such as usurious loan contracts, then his work is a forbidden form of assistance, due to the Almighty's saying: "And do not cooperate in sin and aggression." The Prophet, peace and blessings be upon him, cursed the devourer of usury, its payer, its scribe, and its two witnesses, and said: "They are all alike."

If working in this field necessitates authenticating forbidden contracts and he cannot refuse them, then it is unlawful, and he would be assisting those involved in usury and sharing their sin. The wage he receives for such work is an unlawful wage, which he must dispose of by spending it on the interests of Muslims or giving it to the poor and needy.

He must seek another job from which he can earn a lawful livelihood, and let him know that whoever abandons something for the sake of Allah, Allah will compensate him with something better. As for authenticating legitimate contracts where the price might involve a usurious loan, there is no harm in authenticating them.