They allowed him to keep the extra money as a gesture of 'goodwill'.
a 'goodwill' ambassador on a 'goodwill' tour/mission
She has/feels 'goodwill' toward all her coworkers.
(..) And sure I am, two men there are not living to whom he more adheres If it will please you to show us so much kindness and goodwill... ...as to expend your time with us a while for the supply and profit of our hope... ...your visitation shall receive such thanks as fits a king's remembrance (..)2015 Hamlet