Melito, Bishop of Sardis, is the author of the earliest surviving Easter praeconium, a liturgical proclamation of the Resurrection message, the precursor of our sung Easter Exsultet.

From the “Oxford Dictionary of Late Antiquity” edited by Professor Oliver Nicholson (with his permission):-

Exultet  (Lat. “Let it rejoice”).  Opening of a hymn chanted by the deacon at the Easter vigil in praise of the Resurrection and of the Paschal candle representing the Light of Christ (praising also the bees who made the candlewax). 

This Paschal praeconium is traditionally attributed to Ambrose of Milan, but probably came into use in the 7th century.    

The earliest liturgical announcement of the Resurrection to survive in full is Melito of Sardis On the Pasch (late 2nd century).  Constantine I provided lights for churches at Easter (Eusebius VCon IV, 22); his Oration to the Saints was delivered to Christians at court during a paschal celebration.  

Augustine’s lines praising candlelight (City of God XV, 22) may derive from such an Easter hymn.  A letter attributed to Jerome declines a request from a deacon to write something suitable (CPL 621).   Two Paschal Praeconia survive by Ennodius of Pavia (CPL 1500).

OPN, MFC

Exultet (CPL 162):  ed. B. Capelle in Misc. Mercati I, 219-46.

H.A.P. Schmidt (ed.) Hebdomada Sancta (2 vols., 1957) I, 126-38;  II, 627-50

New Grove Music 8, s.v. Exultet, p.  477-480 (Huglo and Kelly).