and etymology:

"Deterge" is not a particularly common word in the English language. However, it  is related to a word with which most of us are likely familiar: "detergent."  Like "detergent," "deterge" comes (possibly by way of French "déterger") from  the Latin verb "deterg?re," itself from "de-" and "terg?re" ("to wipe").  "Deterge" entered the English language in the early 1600s and has primarily been  used in medical contexts, such as Ambrose Cooper's 1757 recipe for Vulnerary  Water: "This Water is of excellent Service in Contusions, Tumors attending  Dislocation, Fractures and Mortifications, the Part affected being bathed with  it. Some also use it to deterge foul Ulcers, and incarn Wounds…."

It doesn't take much guesswork to figure out where this is headed, eh? :)  The book of John is our first stop in Scripture:

This is the message we have heard from Him and announce to you, that God is Light, and in Him there is no darkness at all.   If we say that we have fellowship with Him and yet walk in the darkness, we lie and do not practice the truth; but if we walk in the Light as He Himself is in the Light, we have fellowship with one another, and the blood of Jesus His Son cleanses us from all sin. If we say that we have no sin, we are deceiving ourselves and the truth is not in us.  If we confess our sins, He is faithful and righteous to forgive us our sins and to cleanse us from all unrighteousness.  If we say that we have not sinned, we make Him a liar and His word is not in us.  - 1 John 1:5-10

Part of the traditional events that begin the Sabbath evening include:

• Singing of songs (such as Shalom Aleichem)
• Recitation of Psalms (Psalm 92, 95, and others)
• Blessings of the family (the husband blesses the wife, the wife blesses the husband, the father blesses the children, etc)
• Recitation of the Aaronic benediction (Numbers 6:24-26)
• Kiddush (which means "sanctification") is a prayer recited on the Sabbath and Festivals, usually over a cup of wine, to consecrate the day. (see Answers.com)
• Washing of hands

The hand washing ceremony is usually performed with a two handled cup and a specific blessing is recited.  These passages from Scripture are usually read:

Who may ascend into the hill of the LORD? And who may stand in His holy place?  He who has clean hands and a pure heart, Who has not lifted up his soul to falsehood And has not sworn deceitfully.  Psalm 24:3-4

Draw near to God and He will draw near to you. Cleanse your hands, you sinners; and purify your hearts, you double-minded. - James 4:8

The last of the verses that comes to mind is from 2 Timothy 2:

Therefore, if anyone cleanses himself from these things, he will be a vessel for honor, sanctified, useful to the Master, prepared for every good work. - 2 Timothy 2:21

(See 2 Timothy 2:14-21 for context)

To Him who cleanses us from all sin be the glory and honor forever.  Amen.