In the Orthodox Church there is a good custom of continuous reading of the Psalter over the body of the deceased (except for the time when memorial services or funeral lithiums are performed at the grave) before his burial and in memory of his burial.
The reading of the Psalter for the dead has its origins in ancient times. It brings great consolation to the departed both in itself, as reading the word of God, and as testifying to the love of their living brothers for them.
The reading of the Psalter begins at the end of the “Following the Exodus of the Soul.” The Psalms should be read with tenderness and contrition of heart, slowly, and carefully delving into what is being read. The greatest benefit comes from reading the Psalter by the relatives of the deceased: it testifies to great love and zeal for their neighbors who are remembered. The Lord will accept the feat of reading not only as a sacrifice for those remembered, but also as a sacrifice for those who work in reading themselves.
It is more decent for the reader of the Psalter to stand if his state of health does not force him to sit down.
In the Apostolic Decrees it is commanded to perform psalmody, readings and prayers for the departed on the 3rd, 9th and 40th day. But mainly the custom has been established to read psalms for the departed for 3 days or 40 days, including the day of death.
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The Psalter consists of 20 sections - kathisma, each of which is divided into three “Glories”. Before reading the first kathisma, the prayers laid before the beginning of the reading of the Psalter are said. At the end of the reading of the Psalter, prayers are said after reading several kathismas or the entire Psalter.
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Text of the Psalter for the Dead: Project Reading the Psalter (Funeral Psalter)