en_obs-tn/content/13/03.md

Three days later

In other words, three days after they arrived at Mount Sinai and God first spoke to them.

prepared themselves spiritually

This refers to ceremonial cleansing in preparation to meet with God. This could be translated as, "got ready to meet with God" or, "prepared themselves to meet with God."

loud trumpet blast

This could be translated as, "and a loud sound came from a horn" or, "and a horn was blown and it made a loud sound" or, "and they heard the loud sound of a horn blowing." Trumpets were made out of ram's horns. They were used that day to call the people to gather at the mountain and meet with God.

Only Moses was allowed to go up

This could be translated as, "God permitted Moses to go up, but he did not permit anyone else to go up."