'Reward' in the Bible

Then Ahimaaz the son of Zadok again said to Joab, "{Come what may}, please let me also run after the Cushite." Joab asked, "Why [are] you wanting to run, my son, when for you there is no {messenger's reward}?"

Your servant shall go over the Jordan with the king a little way, but why should the king recompense me with this reward?