What is the method of the permissible and the prohibited mudarabah?

Question:
The Islamic Bank gives monthly, unspecified profits in exchange for the funds deposited in it by citizens. Are those profits lawful or forbidden?

Answer:
This requires a detailed explanation:
If the profits were obtained through buying and selling and mudarabah, and a profit was realized, and he gave it to him according to the condition between them: by half, or by a third; then there is no harm.
And if his profits are fixed: in every month you get so many riyals, two riyals, 5%, 10%, then this is riba and is not permissible.
As for if it is not, you take their money and put it in cars, in vessels, in other things you sell, necessities you sell, and you give his share of the profit between you in halves, or thirds, or quarters, you take your right and give him his right of the profit; then there is no harm with this, like: the mudarabahs, like giving your brother, for example, ten thousand riyals, and putting it in the goods you see, saying: sell them and the profit is between us, then there is no harm with this, this is permissible by the consensus of the Muslims, and this was the reality in the early eras: in the time of the Prophet (peace and blessings be upon him) and before him and after him, this is called: the mudarabah, and it is the musharakah, so if the one who receives the money is in this condition that you take the money and put it in the goods, you sell them for profit, you sell between the owner of the money and the bank by half or by a third; then there is no harm.