God rest ye merry gentlemen

In the UK, the de facto baseline reference version is that adopted by Carols for Choirs, OUP, (1961):

1. God rest ye1 merry, gentlemen,

Let nothing you dismay,
For Jesus Christ our Saviour
Was born upon this day,
To save us all from Satan's power
When we were gone astray:
O tidings of comfort and joy,
comfort and joy,
O tidings of comfort and joy.
2. In Bethlehem, in Israel,:2
This blessèd Babe was born,
And laid within a manger
Upon this blessèd morn,
The which His Mother Mary
Did nothing take in scorn:
O tidings ...
3.From God our heavenly Father
A blessèd angel came,
And unto certain shepherds
Brought tidings of the same,
How that in Bethlehem was born
The Son of God by name:
O tidings ...
4. The shepherds at those tidings
Rejoicèd much in mind,
And left their flocks a-feeding
In tempest, storm and wind,
And went to Bethlehem straightway,
This blessèd Babe to find:
O tidings ...
5. But when to Bethlehem they came,
Whereat this Infant lay,
They found Him in a manger,
Where oxen feed on hay;
His mother Mary kneeling,
Unto the Lord did pray:
O tidings ...