And she gave birth to her firstborn son. She wrapped him in swaddling clothes and laid him in a manger, because there was no room for them in the main room of the house. (Luke 2:7)

Joseph and Mary arrived in Bethlehem. Since they were poor and the lodgings that might have been within reach of their resources were already taken by others who had come from afar for the same reason, and finding no place to stay, they had to take shelter in a public shed. (Golden Legend by Jacobus de Voragine)

This scene is an interpretation of the Gospel of Luke that mentions that Mary and Joseph couldn’t find a place to stay at the moment of the birth. However, Apocryphal Gospels and the Golden Legend explain that the birth took place in a humble manger due to the couple's economic situation. Over time, popular tradition added the element of seeking lodging from door to door, with Mary and Joseph traveling on a mule and being turned away. This was especially spread through sacramental plays and convent traditions, as mentioned in the posada songs by Saint John of the Cross and Blessed Ana of Saint Bartholomew, both 16th-century Carmelite figures. This tradition carried a more spiritual and moralizing message, urging believers to prepare the dwelling of their heart and not to close the door to the Son of God.