3] Here, St. John is simply repeating a teaching common to the Church. St. Macarius Of Alexandria (having received the teaching not from men but from an angel) explains: "When
an offering (i.e., the Eucharist) is made in Church on the third day, the soul of the departed receives from its guardian angel relief from the sorrow it feels as a result of the separation from the body.

In the course of two days the soul is permitted to roam the earth, wherever it wills, in the company of the angels that are with it. Therefore, the soul loving the body, sometimes wanders about the house in which its body has been laid out, and thus spends two days like a bird seeking its nest.
But the virtuous soul goes about those places in which it was wont to do good deeds.

Forty Days After

Why do Orthodox pray for a deceased person forty days after their death?

St. Macarius of Alexandria is alleged to have written an apocryphal homily on the reason why Memorial Services or Panahidas are customarily celebrated on the 3rd, 9th and 40th day after a death.

St. Macarius asked an Angel who accompanied him the reason for services on these days, on the anniversaries of the name-day, and day of death of a person. This is what the angel told him:

On the third day when the body is brought to the Church, the dead person receives from his Guardian Angel relief from the grief which he may have felt at parting from his body. He receives this because of the prayers of oblation and praise which are offered for him and there arises in him a blessed hope. For during the past two days his soul was permitted to wander over the earth with angels accompanying it. Since the soul loved its body, it sometimes hovered around the place where it had parted from the body, and other times it was around the coffin where its body had been placed. In this way, it passed those few days like a bird which looks for its nesting-place. Some souls wander through those places where at one time it did deeds of righteousness and good.

Jesus, who rose from the dead, commanded that on the third day every soul shall be brought to heaven, in imitation of His own Resurrection, that it may do reverence to God. This is why the Church has the blessed custom of celebrating oblation and prayers on the third day.

After the soul has done reverence to God, it is shown the places where the saints lived and the beauty of Paradise. The soul sees these during the 3rd to the 9th day and it glorifies God, the Creator. When the soul has seen all these things, it changes and it forgets all the sorrows which it felt in the body. But if it is guilty of sin it begins to wail and reproach itself for passing its time on earth in a heedless way and not obeying God so that it could have these same glories and graces. After seeing the joys of the just for these six days, the Angels lead the soul to God again. Therefore the Church does well to celebrate a service and oblation for the soul on the ninth day.

After this second reverence to God, He commands that the soul be taken to hell and shown the places of torment, the different divisions of hell and the various torments of the ungodly which causes the souls of sinners to groan continually and to gnash their teeth. Various places of torment are visited for thirty days and the soul trembles fearing that it will be condemned to live there.

On the fortieth day, the soul is again taken to do reverence to God and then the Judge determines the right place of its incarceration according to its deeds. This is the reason why the Church does right in making mention on the fortieth day of its baptized dead.

We can readily see that the reason for the Memorial Service or Panahida on the third, ninth and fortieth day is because the souls are brought before God on these days. Having services on the fortieth day is especially important because the soul is brought for judgment at that time.