In the Russian Orthodox tradition, a memorial service for the deceased is held on the day of the funeral, as well as on the ninth (nine) and fortieth (fortieth) days after death. Why?
Nines
The commemoration of the deceased on this day is performed in honor of the nine ranks of the angels, who, as servants of the Heavenly King, intercede for mercy on the departed.
According to Orthodox patristic tradition, after the third day, the soul of the deceased, accompanied by angels, enters the heavenly abodes and contemplates their unspeakable beauty, until the ninth day she is shown the afterlife. She remains in this state for six days. Then, on the ninth day, the Lord commands the angels to present the soul to Him for worship, and the soul with trembling and fear again appears before Him. Remembrance and prayers on this day help her to pass this test with dignity, all requests to the Lord - for the establishment of the soul of the deceased along with the saints.
On this day, a panikhida is served. It is customary to invite only close friends and relatives of the deceased to the commemoration on this day. From 9 to 40 days, the soul goes to hell, where it observes the torment of sinners.
Sorokoviny
Promotional video:
On the 40th day, the soul of the newly departed, after being in Hell, is delivered for the third time by the angels before God, who gives it a place until the Last Judgment and the final determination of the eternal afterlife fate. One of three dates in the Orthodox tradition, marked for a special commemoration of the newly departed: the third day, the ninth day, the fortieth day. Two dates - the third day and the fortieth day - coincide with the milestones in the earthly life of Jesus Christ: on the third day, after his bodily death, He rose again, on the fortieth day after his resurrection, He ascended to God.
