As a genre, the lullaby seems to attract more than its fair share of attention from composers who endeavor to set Christmas texts, and more than its fair share of attention from those who like to listen to Christmas music. (Perhaps the latter explains the former.) Those, like myself, who take a more compelling fancy to the theological red meat of the Johannine prologue and Ephesians 1 at this time of year (per the lectionary today) than to the over-sentimentalized meta-image of the Virgin Mother swaddling and nursing and singing to her offspring simply have to ... well, "get over it" at times, and just go with the flow of feeling evoked by the manger scene.
RVW pays obligatory homage to his lullaby muse with this text by the 17th century poet William Ballet. It is scored for women's voices and a relatively light (by Vaughan Williams standards) orchestral accompaniment, and is surpassingly lovely.
Sweet was the song the Virgin sang,
When she to Bethlem Juda came
And was delivered of a son,
That blessèd Jesus hath to name:
“Sweet babe,” sang she, “my son,
And eke a saviour born,
Who hast vouchsafed from on high
To visit us that were forlorn.”
“Sweet babe,” sang she,
And rocked him sweetly on her knee.