The villancico is attributed by some sources to Mateo Flecha the Elder, who died in 1553; it has also been described as anonymous.The song also bears a strong resemblance to another villancico, Falalanlera, by Bartolomeu Càrceres, a [bad word] It is known from a single source, the Cancionero de Upsala, published in 1556 in Venice; a unique copy is preserved at the library of the University of Uppsala. The song appears as the fortieth song of that collection. Daniel R. Melamed described the song as "redoutable", and mentions it as a contender for the best known piece of Renaissance music.

Riu, riu, chiu 
La guarda ribera 
Dios guarde el lobo 
De nuestra cordera.

El lobo rabioso la quiso morder,
Mas Dios poderoso la supo defender;
Quisole hazer que no pudiesse pecar,
Ni aun original esta Virgen no tuviera.
Riu, riu, chiu, etc.

Este qu’es nascido es el gran monarca,
Cristo patriarca de carne vestido;
Hanos redimido con se hazer chiquito,
Aunqu’era infinito, finito se hizera.
Riu, riu, chiu, etc. 

Muchas profecias lo han profetizado,
Y aun en nuestros dias lo hemos alcancado.
Dios humanado vemos en el suelo
Y al hombre nel cielo porqu’er le quisiera.
Riu, riu, chiu, etc.

Yo vi mil Garzones que andavan cantando,
Por aqui bolando, haciendo mil sones,
Diziendo a gascones Gloria sea en el cielo,
Y paz en el suelo qu’es Jesus nascieta.
Riu, riu, chiu, etc.

Este viene a dar a los muertos vida
Y viene a reparar de todos la caida;
Es la luz del dia aqueste mocuelo;
Este es el cordero que San Juan dixera.
Riu, riu, chiu, etc.
Pues que ya tenemos lo que desseamos,
Todos juntos vamos presentes llevemos;
Todos le daremos nuestra voluntad,
Pues a se igualar con el hombre viniera.
Riu, riu, chiu, etc

TRANSLATION:

Riu, riu, chiu (nightingale's sounds)
The river bank protects it,
As God kept the wolf from our lamb

The rabid wolf tried to bite her
But God Almighty knew how to defend her
He wished to create her impervious to sin
Nor was this maid to embody original sin
Riu, riu, chiu (nightingale's sounds)
The river bank protects it,
As God kept the wolf from our lamb

 [bad word] to give life to the dead
 [bad word] to redeem the fall of man
This child is the light of day
He is the very lamb Saint John prophecied

Riu, riu, chiu (nightingale's sounds)
The river bank protects it,
As God kept the wolf from our lamb

thousand singing herons
I saw passing,
Flying overhead, sounding
thousand voices
Exhulting, "Glory be in the
heavens, and peace on earth,
for Jesus has been born."

Riu, riu, chiu (nightingale's sounds)
The river bank protects it,
As God kept the wolf from our lamb

 [bad word] to give life to the dead
 [bad word] to redeem the fall of man
This child is the light of day
He is the very lamb Saint John
prophesied

Riu, riu, chiu (nightingale's sounds)
The river bank protects it,
As God kept the wolf from our lamb

thousand singing herons
I saw passing
Flying overhead, sounding
a thousand voices
Exhulting, "Glory be in the
heavens, and peace on earth
for Jesus has been born."

Riu, riu, chiu (nightingale's sounds)
The river bank protects it,
As God kept the wolf from our lamb. 

Испанский духовный кант 16 века.