King James Bible
"And the LORD said unto Moses, Go unto the people, and sanctify them to day and to morrow, and let them wash their clothes,"
God commands Moses to serve as mediator between himself and Israel, establishing the pattern of Moses as covenant intermediary. This occurs at Mount Sinai where God is about to reveal himself and give the law to the newly freed nation. The people must undergo a two-day consecration process to prepare for encountering God's holiness on the third day. Sanctification involves ritual purification and mental preparation, separating the people from common activities for sacred purposes. Washing garments represents outward purification that symbolizes inner cleansing, a concrete act demonstrating readiness to meet God. This physical preparation teaches that approaching the holy God requires both spiritual and practical measures of reverence.