Is it permissible to spend a financial incentive that is still being disbursed in the name of a colleague who has left work, to use it to purchase supplies for the office, knowing that the questioner will only make the disbursement and hand it over to the office secretary?

It is not permissible to take extra money, whether it is given to an office secretary or not, because it is consuming wealth unjustly and betraying a trust. Allah Almighty says: {O you who have believed, do not consume one another’s wealth unjustly} and {O you who have believed, do not betray Allah and the Messenger or betray your trusts while you know [the consequence].} The obligation is to keep the money as it is or to inform the competent authority.