Once in royal David's city,
Stood a lowly cattle shed,
Where a mother laid her baby,
In a manger for His bed:
Mary was that Mother mild,
Jesus Christ, her little child.
Once in Royal David's City was a poem written by Cecil Frances Alexander and first published in 1848 in the hymnbook Hymns for Little Children. A year later, the English organist Henry Lord Gauntlett set the poem to music. Cecil Frances Alexander is also known for her hymn All Things Bright and Beautiful.
The King's College Choir in Cambridge, England has been singing the song since 1919 in its Festival of Nine Lessons and Carols. Following Doctor Henry Mann's arrangement, the first verse is sung by a boy chorister, the second by the choir, and the third by the congregation. The Mormon Tabernacle Choir has recorded the song https://www.youtube.com/watch?v=zOMywz3cz2k.