It is considered a sacrament of the Church mysteries and is called the Sacrament of Holy Unction. It is always performed in hope of healing the soul and the body.
Many Church Fathers and teachers mention this sacrament.
The Book of the Twelve Apostles (Didache – second century AD) contains a text about the use of oil in the church:
“O Lord our God, do Thou sanctify this oil and instill in it the gift of sanctification to those who distribute it and those who accept it. Thou hast indicated that kings, priests and prophets of old be anointed. Grant us also to be anointed for the healing of the soul and body. ”
Many testimonies from early Christianity and the holy fathers mention this sacrament.
St. John Chrysostom recommends that Holy Unction be used in all sickness cases, not limiting it to extreme illnesses, when the sick is in agony of death.