LETHE (Lêthê), the personification of oblivion, is called by Hesiod (Theog. 227) a daughter of Eris. A river in the lower world likewise bore the name of Lethe.
Source: Dictionary of Greek and Roman Biography and Mythology.
CLASSICAL LITERATURE QUOTES
Hesiod, Theogony 226 ff (trans. Evelyn-White) (Greek epic C8th or C7th B.C.) :
"But abhorred Eris (Strife) bare painful Ponos (Toil), and Lethe (Forgetfulness), and Limos (Starvation), and the Algea (Pains), full of weeping, the Hysminai (Fightings) and the Makhai (Battles), the Phonoi (Murders) and the Androktasiai (Man-slaughters), the Neikea (Quarrels), the Pseudo-Logoi (Lies), the Amphillogiai (Disputes), and Dysnomia (Lawlessness) and Ate (Ruin), who share one another's natures, and Horkos (Oath)."
Orphic Hymn 85 to Hypnus (trans. Taylor) (Greek hymns C3rd B.C. to 2nd A.D.) :
"Thanatos (Death), and Lethe (Forgetfulness) with oblivious stream, mankind thy [Hypnos' (Sleep's)] genuine brothers justly deem."
Pseudo-Hyginus, Preface (trans. Grant) (Roman mythographer C2nd A.D.) :
"From Aether (Air) and Terra (Earth) [Gaia] [were born] : Dolor (Pain), Dolus (Deceit), Ira (Rage), Luctus (Lamentation), Mendacium (Lies), Jusjurandum (Oath), Ultio (Vengeance), Intemperantia (Intemperance), Altercatio (Altercation), Oblivio (Forgetfulness) [i.e. Lethe], Socordia (Sloth), Timor (Fear), Superbia (Pride), Incestum (Incest), Pugna (Combat)."
[N.B. Oblivio is the Latin translation of Lethe.]
Statius, Thebaid 10. 90 ff (trans. Mozley) (Roman epic C1st A.D.) :
"[In] the hollow recesses of a deep and rocky cave . . . [are] set the halls of lazy Somnus (Sleep) [Hypnos] and his untroubled dwelling. The threshold is guarded by shady Quies (Quiet) and dull Oblivio (Forgetfulness) [Lethe] and torpid Ignavia (Sloth) with ever drowsy countenance. Otia (Ease) and Silentia (Silence) with folded wings sit mute in the forecourt."
Other references not currently quoted here: Plutarch Table-Talk 7.5, Scholiast on Pindar's Olympic Odes 3.177.