Leviticus 16:1-5 New International Version (NIV)
The Day of Atonement
16 The Lord spoke to Moses after the death of the two sons of Aaron who died when they approached the Lord. 2 The Lord said to Moses: “Tell your brother Aaron that he is not to come whenever he chooses into the Most Holy Place behind the curtain in front of the atonement cover on the ark, or else he will die. For I will appear in the cloud over the atonement cover.
3 “This is how Aaron is to enter the Most Holy Place: He must first bring a young bull for a sin offering and a ram for a burnt offering. 4 He is to put on the sacred linen tunic, with linen undergarments next to his body; he is to tie the linen sash around him and put on the linen turban. These are sacred garments; so he must bathe himself with water before he puts them on. 5 From the Israelite community he is to take two male goats for a sin offering and a ram for a burnt offering.
Aaron needed to spend hours preparing himself to meet God. But we can approach God any time. What a privilege! We are offered easier access to God than the High Priests of the Old Testament. But, never forget God is holy, and do not approach carelessly. Jesus opened the way to God. It is still important to prepare our hearts as we draw near to God in prayer.