Is one who leaves his salary in the bank for a period ranging between 3 and 4 months before transferring it, sinful, knowing that he is unable to transfer it monthly and does not take interest on the amount?

If the bank is usurious (Riba-based), the money should be withdrawn immediately upon deposit, because its retention assists the bank in its forbidden dealings, as Allah Almighty says: "And cooperate in righteousness and piety, but do not cooperate in sin and aggression." However, if you need to keep the salary for a period to protect it from loss, and there is no Islamic alternative, then there is no blame. If usurious benefits (interest) accrue, they must be disposed of by spending them on Muslim welfare projects or for the poor and needy.