When it is said
Pray it at the moment you feel yourself going under.
It is short enough to say under your breath, wherever you are.
Orthodox churches read the story as the Gospel of the ninth Sunday after Pentecost.
Where it comes from
Author known
Walking on the water
Jesus had sent His disciples ahead by boat and came to them late in the night, walking on the sea. When Peter asked to come to Him on the water, Jesus said, “Come.” Peter walked toward Him until he saw the wind. Then he was afraid and began to sink, and he cried out, “Lord, save me!” At once Jesus reached out His hand and caught him (Matthew 14:22-31).
Caught like a falling bird
The preacher St John Chrysostom gave a sermon on this story. He noticed that Peter did not ask to walk on the water. He asked to come to Jesus, and Chrysostom put that down to love. He compared Christ to a mother bird who carries a fledgling back to the nest on her wings when it has left too soon and starts to fall.
St John Chrysostom, Homily 50 on Matthew, in the 1888 English translation
The Scripture in it
But when he saw the strength of the wind, he was afraid and, beginning to sink, cried out, “Lord, save me!”
Save me, O God, for the waters are up to my neck. I have sunk into the miry depths, where there is no footing; I have drifted into deep waters, where the flood engulfs me.
Bible text: Berean Standard Bible, public domain.
In Greek
Κύριε, σῶσόν με.
From Matthew’s Gospel in Greek (14:30), on Greek Wikisource.