Is a retirement pension from a usurious bank considered impermissible (haram), like the salary paid to an employee who is still actively working?

Working in a Riba-based bank, and the salary and post-retirement benefits received from it, are unlawful because it constitutes assistance in sin and is the effect of an unlawful contract. It is not permissible to benefit from the money obtained from it; rather, it should be spent on general Muslim welfare, except in cases of extreme necessity.