Jeremiah 13:1 NASB
13 Thus the Lord said to me, “Go and buy yourself a linen waistband and put it around your waist, but do not put it in water.”
What was the significance of not putting the linen waistband in water?
The New International Version Study Bible makes these comments regarding the linen belt:
Linen - the material of which the priests' garments were made (Ezekiel 44:17-18) are symbolic of Israel's holiness as a "kingdom of priests" (Exodus 19:6). The linen belt is a symbol of the formerly intimate relationship between God and Judah.
Do not let it touch water - Do not wash it - symbolic of Judah's sinful pride (as mentioned in verse 9).
Jeremiah 13:7 says that after the linen belt was dug up, it "was ruined and completely useless". The NIV Study Bible refers to Leviticus 26:39 which describes how God's people in exile would waste away because of their sins.
Jeremiah was commanded to perform symbolic acts to illustrate God's message. Jeremiah 13:11 says:
For as a belt is bound round a man's waist, so I bound the whole house of Israel and the whole house of Judah to me to be my people for my renown and praise and honour. But they have not listened.
The following verses about the wineskins is another example of using imagery to point towards the coming destruction of Judah's leaders and people.
The significance of the Lord's instruction to Jeremiah not to put the linen belt in water is obedience.
I believe the significance can be seen when you read that verse in context. If you read further the belt is then hidden in a rock and becomes marred. I believe the the girdle represents the belt in the armor of God. ( Ephesians 6:11-13) belt holds the sword for battle. The sword is The Word of God. This belt was not to be be immersed in water, which could represent the Word of God. Instead the girdle is marred making it worthless and unable to hold the protection (sword). I believe this is meant to describe the condition of Israel due to their disobedience. They are not girded with the belt of truth or Sword of the Spirit, therefore they cannot protect themselves from spiritual enemies.
From a website about how to care for linen garments:
Linen is actually one of the few fabrics that gets stronger when it is wet. Pure linen fibers don’t stretch, and they are resistant to abrasion.
Perhaps God is telling Jeremaih to keep the linen dry (which is a weaker state for the fabric) and then weaken it further by mashing/folding/burying it. See this further note about linen fibers:
However, because the fibers of linen fabric have such a low elasticity, they can break if they are folded and bent in the same area over and over.
God is making a statement about Israel and Judah- they could be strong but are not; and because they hide from God and do not keep themselves 'clean', they further weaken and will be ruined.
In Matthew 9:16, Jesus talks about unshrunk cloth -- unwashed cloth. Perhaps this is calling back to the story in Jeremiah, in terms of being washed by God.