Suratul kawthar explains about a river (al kawthar) in jannah that Allah has promised our prophet (saw). The believers will drink from it in the day of judgement. May Allah make us among them Inshallah ameen.

Suratul kafirun was a surah that was revealed to answer the disbelivers when they invited the prophet (saw) to worship their idols for one year so that in return they worship Allah in the next year. So Allah answered them by telling the prophet to say to them.....