this is a traditional spanish christmas carol, performed by the trombone trio comprised of me, myself, and I.

here are the words, in case you wanted to know:
A la nanita nana, nanita ea nanita ea,
A la nanita nana, nanita ea nanita ea,
Mi Jesus teine sueno, bendite sea, bendito sea,
(Sleep, sleep, my little Jesus,)
(May peace attend Thee, May peace attend Thee.)
fuentecilla que corres clara y sonora
(To the world, little Savior, New hope thou'rt bringing)
Ruisenor q'en la selva cantando lloras,
(All the world, little Savior, Thy praises singing,)
Callad mientras la cuna se balancea.
(God's angels hov'ring o'er Thee chant alleluia.)
A la nanita nana, nanita ea.
A la nanita nana, nanita ea.