Paschal troparion
The Paschal troparion or Christos anesti (Greek: Χριστὸς ἀνέστη) is the characteristic hymn for the celebration of Pascha (Easter) in the Eastern Orthodox Church and those Eastern Catholic Churches which follow the Byzantine Rite.
Like most troparia it is a brief stanza often used as a refrain between the verses of a Psalm, but is also used on its own. Its authorship is unknown, though it has been attributed to Romanos the Melodist. It is sung in the first plagal (or fifth) Tone. It is often chanted thrice (three times in succession).