Matthew 2:13-23. After the wise men had viited Jesus they returned back East another way. Meanwhile Joseph was told to get out of Bethlehem and flee to Egypt. Herod was furious that he had been had and murdered all male children under the age of 2 in and around Bethlehem. Herod died soon after, and the little family went back to Nazareth. (As a side note, in the Middle East Christians are nowadays called Nazarenes.)
In Exodus 19, time had come to visit Mount Sinai. God declared that the Israelites would be a Kingdom of Priests and a holy nation. The chapter deals with the three-day consecration that was to occur before Moses went up to meet with God.
Exodus 20. Moses went up Mount Sinai, and there God gave him the ten commandments.