What did the heavenly host say when praising God before the shepherds?

Answer: Glory to God in the highest

A great multitude of the heavenly host praised God: 'Glory to God in the highest, and on earth peace...'

“And suddenly there appeared with the angel a great multitude of the heavenly host, praising God and saying: “Glory to God in the highest, and on earth peace to men on whom His favor rests!””— Luke 2:13-14 (BSB)