Panel 4 of Cantiga 55 of the Cantigas de Santa Maria of Alfonso X

The Nun who Left the Convent (Atant’ é Santa Maria/ de toda bondade bõa)
   A nun faithfully said the hours before a statue of the Virgin.
   However, the devil tempted her to run away to Lisbon with an abbot.
   When she became pregnant, the abbot left her and she returned to her convent. She discovered that she had not been missed in her absence.
   As the time came for her to deliver her child, she continued to pray to the Virgin. She asked Mary to save her from disgrace, and the Virgin made an angel take the child from her to be raised elsewhere. The woman grew old and grey, but did not forget her child.
   One day, when the nuns were chanting vespers, a handsome young man entered the church. He joined them and sang the Salve Regina. The nun realised it was her son. He also recognised her.
   When they had been informed of the miracle, the nuns, who numbered more than one hundred, praised the Virgin.

Source: Este livro, com’ achei, fez á onr’ e á loor da virgen santa maria’. El proyecto de las Cantigas de Santa María en el marco del escritorio regio. Estado de la cuestión y nuevas reflexiones” en Las Cantigas de Santa María, el Códice Rico, Ms. T-I-1, RBME, Madrid, Testimonio Editorial – Patrimonio Nacional, 2011, pp. 43-78.

List of Cantigas de Santa Maria