This delightful old English prayer said by children and their parents at bedtime has long ago been shortened to only its last verse. There is more (as I was taught):
Matthew, Mark, Luke and John,
Bless the bed that I lie on.
The are four corners to my bed,
Four angels round my head,
One to watch, and one to pray,
And two to bear my soul away.
Now I lay me down to sleep,
I pray the Lord my soul to keep.
If I should die before I wake,
I pray the Lord my soul to take.
If you know more of the tradition of this prayer please share it.