I Samuel - Chapter 2
I Am Sam. (Sam I Am.)
When Chana brought Shmuel to the Tabernacle, she sang a song of praise to Hashem that is full of prophetic meaning. As with Deborah's song in Judges, there's no way a synopsis can do it justice, so make sure you read it for yourself.
Shmuel remained with Eli in the Tabernacle, to be trained in the service of Hashem. Eli was assisted by his two sons, Chofni and Pinchas. Chofni and Pinchas are described by the Navi as "lawless" because they abused their authority. They used force and intimidation to take portions of sacrifices beyond those to which they were entitled. Eli got wind of the people's complaints against his sons and chastised them, but it was too little, too late. They kept on with their evil behavior, but as they were declining, Shmuel's star was rising.
G-d sent a prophet (possibly Elkanah) to Eli with a dire message. Because of his sons' behavior, the hereditary position of High Priest would be removed from Eli (a descendant of Aaron's son Itamar) and given to another branch of Aaron's descendants. Furthermore, none of Eli's descendants would live to see old age. The sign G-d gave was that Chofni and Pinchas would die on the same day. (The merit of Torah study and mitzvos could mitigate the curse; descendants of Eli were among the sages of the Talmud - see Rosh Hashana 18a.)