This is the O Antiphon for today, 18th December.
O Adonai, et Dux domus Israel,
qui Moysi in igne flammae rubi apparuisti,
et ei in Sina legem dedisti:
veni ad redimendum nos in brachio extento.
O Adonai, and leader of the House of Israel,
who appeared to Moses in the fire of the burning bush
and gave him the law on Sinai:
Come and redeem us with an outstretched arm.