I bind unto myself the Name,
The strong Name of the Trinity;
By invocation of the same.
The Three in One, and One in Three,
Of Whom all nature hath creation,
Eternal Father, Spirit, Word:
Praise to the Lord of my salvation,
Salvation is of Christ the Lord.http://prayerfoundation.org/st_patricks_breastplate_prayer.htm
Genesis 18: The Three Visitors
1The Lord appeared to Abraham near the great trees of Mamre while he was sitting at the entrance to his tent in the heat of the day. 2Abraham looked up and saw three men standing nearby. When he saw them, he hurried from the entrance of his tent to meet them and bowed low to the ground.
3He said, “If I have found favor in your eyes, my lord, a do not pass your servant by. 4Let a little water be brought, and then you may all wash your feet and rest under this tree. 5Let me get you something to eat, so you can be refreshed and then go on your way—now that you have come to your servant.”
“Very well,” they answered, “do as you say.”