What are the requirements for the stipulated reward if it is paid from the treasury/public funds (property in the Imam's possession)?

Primary text

If the reward is stipulated from the Imam's own possession or public funds, it must be known (specified). This is because it functions as a contract of 'ja'ala' involving a specified compensation from known property, thus requiring the reward itself to be known, similar to the reward for returning an escaped slave.