Short answer: it doesn’t. The saying “blood is thicker than water” is not in the Bible. No verse in scripture contains those words or anything close to them.
Where the saying comes from
It is an old European proverb about family loyalty, not a Bible verse.
- The oldest known version is German, from about 1180. It says kin-blood “is not spoiled by water.”
- A related English saying, that blood will “draw unto blood,” appears in John Lydgate’s Troy Book in 1412.
- The modern wording was common in Scottish writing by the 1800s, including Sir Walter Scott.
You may also see a claim that the “original” saying was “the blood of the covenant is thicker than the water of the womb.” No one who makes that claim has shown an old source for it. (Source: “Blood is thicker than water,” Wikipedia.)
What the Bible does say about family
Scripture takes family duty seriously:
“If anyone does not provide for his own, and especially his own household, he has denied the faith and is worse than an unbeliever.” (1 Timothy 5:8)
But it also teaches that a true friend can be closer than a relative, and that God’s people are a family of their own:
“A man of many companions may come to ruin, but there is a friend who stays closer than a brother.” (Proverbs 18:24)
“For whoever does the will of God is My brother and sister and mother.” (Mark 3:35)
“Therefore, as we have opportunity, let us do good to everyone, and especially to the family of faith.” (Galatians 6:10)
So the Bible never says blood ties outrank every other bond. It calls us to care for our own families and to treat fellow believers as family too.
Quote is NOT biblical! And it is misused. “The blood of the covenant is thicker than the water of the womb” meaning the blood oaths made to fellow soldiers, friends, and CHOSEN trusted allies, was thicker than the familial ties(water of the womb) that were often times toxic and betrayed. In other words, exactly the opposite of how it is used today.