Die Walküre
Sieglinde goes to prepare a drink for her husband.  She puts a drug in it which will make Hunding sleep deeply.  Siegmund meanwhile is thinking about something his father had promised him.  He had told him that he would thrust a magic sword called “Nothung” into a tree.  No one would get that sword until, one day, when Siegmund found himself in great difficulty, he would be able to pull it from the tree and use it.