This is an Aria from the Opera "Robert le Diable"("Robert the Devil") called "Evocation des Nonnes"("Evocation of the Nuns"). The Opera was composed by Giacomo Meyerbeer with a libretto by Eugène Scribe and Germain Delavigne.

The Opera tells the story of Robert who is the son of the Duke of Normandy. He is in love with Princess Isabelle of Sicily. Robert's father made a deal with the devil of what, as Robert discovers, he is the product. The devil, Bertram, tempts Robert to join him and rule the world together, but Robert resists and defeats Bertram. In the end, Robert is forgiven for his past sins and is reunited with Isabelle.