What is the ruling on a public servant in charge of a governmental department's funds taking some of the surplus money for his personal use, and is it permissible for him to pay his personal expenses from it without the knowledge of the responsible authority?

The official entrusted with government funds must return them in full to the public treasury, even if government dues have been settled and a surplus remains. He must report this surplus and is not permitted to take anything from these excess funds, even if he knows they will not be returned to the public treasury. This is based on the Prophet's (peace be upon him) saying: "Whoever we entrust with anything from what Allah has given us, let him return even the needle and the thread, and take what we have given him." This falls under prohibited embezzlement (ghulul), which is the concealment of anything from war booty, zakat, or financial revenues. Whoever embezzles commits a sin. It is not permissible to take these funds under the pretext that they are ownerless or that the taker is in need, because they are the property of the state. It is forbidden to conceal any part of them or to show favoritism with them.