Tafsiran Imamat 16:30: Kli Yakar, Sforno, Rabbeinu Bahya & Rav Hirsch

Before the Lord you shall be cleansed. For Yom Kippur only atones for those who repent (Shevuot 13). And before God forgives them, each person is obligated to purify themselves from head to toe from all the impurity of sin. Therefore it says, Before the Lord you shall be cleansed, where before serves as a term meaning “prior to.” And I found something even greater than this in the Zohar on the verse Before the elderly you shall rise (Leviticus 19:32), that before the time of old age, a person should rise from their deep sleep to return to God. This is all the more so, the term before [meaning prior to]. And this means, Before the coming of the great and awesome day of the Lord, you shall be cleansed through repentance, and afterward God will purify you through atonement. And it further warns about internal, heartfelt repentance, which is before the Lord, because matters entrusted to the heart are only revealed to God alone. One should not be among the hypocrites who fast, afflict themselves, and increase their supplications in order to be considered righteous, being a generation pure in the eyes of others while not having washed their internal filth. Therefore it says, Before the Lord you shall be cleansed.

כי ביום הזה יכפר, the reason why the other factors mentioned just now are required in addition to the sacrificial service is that if the entire load of achieving atonement were to be placed on the shoulders of the High Priest this would amount only to “downgrading” of the seriousness of the sins which is what the term of כיפור is all about. The individual must prepare himself mentally for obtaining forgiveness from his Maker by these additional measures.

כי ביום הזה יכפר עליכם לטהר אתכם, “for on this day he (the High Priest) will provide atonement for you to purify you, etc.” This verse is an assurance for Jews throughout the generations that the Day of Atonement is a day set aside especially for forgiveness and pardon. On that day the Israelites will be cleansed of all their sins against the Lord. Yom Kippur is ineffective, however, in bringing about forgiveness, atonement, etc., for sins committed against fellow human beings. Only after the person guilty of such sins has been granted forgiveness by the person whom he has wronged will G’d add His forgiveness.
When the High Priest used to recite his confessional on Yom Kippur, he would recite this verse in his prayer. The name of G’d referred to in this verse is the one comprised of 42 letters. This is why we use the formula לפני ה' תטהרו on Yom Kippur in our prayers (a substitution for the tetragram we are not allowed to utter). The words mean לפני שם מ'ב “before the 42-lettered name of the Lord.” The name consists of seven words, the first six representing aspects of the attribute of Mercy, whereas the seventh word represents the attribute of Justice. This is the opinion of my teacher the Rashba. This 42-lettered name is broken down into six times 7 words according to some, whereas others break it down into 14 words of three letters each. [You will find the former version printed before the Sabbath eve hymn לכה דודי, as a prayer beginning with the words אנא בכח. This dates back to the Arizal. Ed.] This prayer was most appropriate as the Day of Atonement is a day on which the attribute of Mercy achieves prominence within the framework of the attribute of Justice. The seventh of the 10 emanations, counting from the bottom מלכות up is גבורה or דין, the attribute of Justice. On that day the High Priest had to plead with the attribute of Justice, i.e. with the Judge who was presiding over all of mankind parading in front of Him, determining their fates for the coming year [if it had not already been decided on Rosh Hashanah. Ed.]