Then, having successfully passed through the toll-houses and bowed down before God, the soul for the course of 37 more days visits the heavenly habitations and the abysses of hell, not knowing yet where it will remain, and only on the fortieth day is its place appointed until the resurrection of the dead . Some souls find themselves (after the forty days) in a condition of foretasting eternal joy and blessedness, and others in fear of the eternal torments which will come in full after the Last Judgment. Until then changes are possible in the condition of souls, especially through offering for them the Bloodless Sacrifice (commemoration at the Liturgy), and likewise by other prayers .
How important commemoration at the Liturgy is may be seen in the following occurrence: Before the uncovering of the relics of St. Theodosius of Chernigov (1896), the priest-monk (the renowned Starets Alexis of Goloseyevsky Hermitage, of the Kiev-Caves Lavra, who died in 1916) who was conducting the re-vesting of the relics, becoming weary while sitting by the relics, dozed off and saw before him the Saint, who told him: “I thank you for laboring with me. I beg you also, when you will serve the Liturgy, to commemorate my parents” — and he gave their names (Priest Nikita and Maria). “How can you, O Saint, ask my prayers, when you yourself stand at the heavenly Throne and grant to people God’s mercy?” the priest-monk asked. “Yes, that is true,” replied St. Theodosius, “but the offering at the Liturgy is more powerful than my prayer.”
+ St. John of Shanghai and San Francisco, Homily on Life after Death
Read entire homily here