When it is said
Isaac wrote it for the night prayers. He told the reader not to begin at once, but to kneel and rise, sign the heart with the cross and stand in silence for a short time until the senses were at rest. Then the reader was to look inwardly to the Lord and say this prayer silently in the heart.
It is not a service prayer. Anyone can say it before morning or evening prayers, after a moment of silence.
Where it comes from
Author known
From his treatise on the night prayers
Isaac was made bishop of Nineveh, near Mosul in Iraq, about AD 670. After only five months he gave up the office and went into the mountains to live with the hermits. He died about AD 700. This prayer stands in his treatise on keeping watch in prayer through the night, which he wrote in Syriac.
Encyclopaedia Britannica, Isaac of Nineveh; Orthodox Church in America, St Isaac the Syrian
What he said would follow
Isaac promised that the heart would suddenly be opened by grace, and that the thoughts would be made pure by remembering the Lord. With the mind gathered and pure, the one praying would begin without disturbance and keep on to the end with delight.
When a thought says hurry
In the same treatise Isaac warns of a thought that whispers in the middle of prayer, telling you to hurry up so that you will soon be finished. He told the reader not to look at it. If it kept pressing, he should stop reciting the psalms, kneel and pray instead.
What the words mean
The Russian version
Isaac’s homilies reached the Greek world early, and the Russian translation was made from the Greek. In that version the prayer opens “Lord Jesus, my God” and asks to be kept from the turmoil of thoughts and the flood of passions. It ends there, without the last lines about standing before God with a clear mind.
Isaac the Syrian, Ascetical Homilies, homily 52, in Russian (Azbyka)
The Scripture in it
For we do not have a high priest who is unable to sympathize with our weaknesses, but we have one Who was tempted in every way that we are, yet was without sin.
Above Him stood seraphim, each having six wings: With two wings they covered their faces, with two they covered their feet, and with two they were flying. And they were calling out to one another: “Holy, holy, holy is the LORD of Hosts; all the earth is full of His glory.”
Bible text: Berean Standard Bible, public domain.