Why does the ruling on the monthly pension amount differ from that on the end-of-service gratuity, even though the insurance funds for both are invested in interest-bearing debt instruments?

The pension salary that the state grants to an employee or to their relatives after their death is permissible, and it is not correct to compare it to commercial insurance. This is because retirement is a right that the state has committed to provide for the employee in return for their service to the nation, and it is not a financial exchange contract. However, if the retirement system deducts a portion of the employee's salary and invests it in something forbidden, such as usury, then it is not permissible to benefit from what resulted from the forbidden investment. Rather, one must dispose of it by giving it to the poor and needy, and only benefit from the amount of the installment that was taken from their salary. As for commercial insurance, it is a contract of gharar (excessive uncertainty) which is forbidden by Sharia, regardless of what the money is invested in.