'Law of the Lord' in the Bible

(as it is written in the Law of the Lord, “Every firstborn male that opens the womb shall be called holy [set apart and dedicated] to the Lord)”

and [they came also] to offer a sacrifice according to what is said in the Law of the Lord [to be appropriate for a family of modest means], “a pair of turtledoves or two young pigeons.”

And when they had done everything [in connection with Jesus’ birth] according to the Law of the Lord, they went back to Galilee, to their own city, Nazareth.