What is the ruling on the salary received during a period of part-time work or absence from duty with the administration's permission, and how can one expiate for the money that is considered lost?

The employee must fully adhere to working hours. If the reduction in working hours came from a manager who does not have the authority, then one should communicate with the responsible administration to confirm the regularity of the permission or their forgiveness. If the absence violates regulations and the responsible party has not forgiven it, then the equivalent amount should be deducted from the salary and returned to the entity or spent on the poor and for the benefit of Muslims. If the duration is unknown, then exert your best judgment to ensure your conscience is clear.