Nunc dimittis
The story told in the book of Luke was that Simeon, who was a Jew, had been promised by the Holy Ghost that he would not die until he had seen Jesus.  When Mary and Joseph brought the baby Jesus to the Temple in Jerusalem for the ceremony of consecration of the firstborn son, Simeon was there, and he took Jesus into his arms and said the words which are now known as the Nunc dimittis.  He was saying to God that he could now die happily because he had seen the Saviour.