What is the ruling of Islamic law on the large sum of money won by the holder of an investment certificate (Group C) issued by Bank XXX, which is drawn monthly, while the holder retains the original value of the certificate?

This transaction is considered gambling (maysir (definition)), which is one of the grave sins, due to the Almighty's saying: "O you who have believed, indeed intoxicants, gambling, [sacrificing to] stone altars, and divining arrows are but defilement from the work of Satan, so avoid it that you may be successful. Satan only wants to cause animosity and hatred between you through intoxicants and gambling and to avert you from the remembrance of Allah and from prayer. So will you not desist?" Therefore, whoever engages in it must repent to Allah, seek His forgiveness, and dispose of what they earned from it.