What is the legality of the annual or monthly return on investment certificates, and what is the ruling on the monthly return from Western banks?

Investment certificates are of two types:

The first: Certificates with increasing value, where their profit is added to the principal amount. The second: Certificates with current returns, where their profit is disbursed every six months while the principal amount remains.

Both of these types are considered a loan with interest, and the interest here is forbidden usury, as Allah Almighty says: (And Allah has permitted trade and forbidden usury).

As for the claim that they are a legitimate Mudarabah (partnership), it is incorrect, because the profit in them is predetermined and not shared, which is an essential condition for a valid Mudarabah. Banks lend money with interest and then give a portion of it to depositors.

Accordingly, what is taken as returns on these certificates is clear usury.