The term in the Russian Church for the day before the feast of the Nativity of the Lord as well as before the feast of the Theophany is sochelnik or sochevnik. This name comes from the Church Slavonic word, sochevo, which means wheat or barley grains, lentils or peas soaked in water. This is the kind of food ordained by the Church rubrics to be consumed on the sochelnik. Orthodox Christians have the pious tradition of not taking any food until the first star appears, which reminds us of the appearance of the star in the East over Bethlehem (Mt. 2:2), bringing the good tidings of the birth of Jesus Christ. This is not something that is prescribed in the Church rubrics. Each person should take on the measure of asceticism suitable to his or her own strength.
On the morning of Christmas Eve are read the Royal Hours, and the Liturgy of St. Basil the Great is celebrated. If Christmas Eve falls on a Saturday or a Sunday, the the Royal Hours are served on the preceding Friday, and the Liturgy of St. John Chrysostom is celebrated, while the Liturgy of St. Basil the Great is served on the day of the Nativity.