This is how I sing it to my grandchildren but I am not sure if it is right.

Little Drummer boy, you're all the world to me,
Dressed up in your little soldier's clothes;
Little drummer boy, do climb upon my knee,
And Rest your curly head in sweet repose.
The day has ended little drummer boy,
Lights out was sounded long ago,
So close your eyes my little drummer boy,
And say goodnight to all your friends and foes,
Reveille will sound in the morning.
Once more on parade you will go.
So close your eyes my little drummer boy
And say goodnight to those who love you so.