Cousin Hatty is Happy doing Right

How glad it makes me feel at night,
When sitting on my mother’s knee,
To hear her whisper “You’ve done right,
My dear child, I am so pleased to see.”
But if I’ve been cross and disobeyed,
Or if I have had my selfish way
With the other children whom I did play
Then I really feel most ashamed and sad.
So if at night I wish to sleep safe n-sound
Especially after a day of delight,
The only way that I have found
Is that each day, I am loving, and do right.

“Safe and sound” was originally applied to a sea vessel that had weathered a storm and was now safe in port, or at least in calmer seas; and sound in that it had suffered no damage in ancient times.

The phrase occurs in the New Testament, describing the way the Prodigal Son’s father receives the Prodigal back to the family. The celebration was said to have occurred because the father had received the son back “safe and sound”. This would have been the translation of the Greek text by the King James translators of 1611

27 And he said unto him, Thy brother is come; and thy father hath killed the fatted calf, because he hath received him safe and sound.
Luke 15:27

Here it is obviously meaning free of anxiety, nightmares  or even restlessness like tossing and turning.