What is the ruling on paying a bribe to succeed in a promotion and benefit from a salary increase, and should one give in charity the money earned until the period for which he would have obtained it without an examination expires?

Paying money to pass an exam and succeed in it is a form of bribery (rishwa), which is forbidden by Islamic law (haram (definition)), and is considered one of the major sins (kabair al-dhunub), due to the deception and fraud it entails towards the employing entity. The Messenger of Allah, peace and blessings be upon him, cursed the briber and the bribed. The fact that a financial increase can be obtained later without an exam does not justify bribery.