The Blood of the Covenant is Thicker Than the Water of the Womb

The Blood of the Covenant is Thicker than the Water of the Womb is the original saying of the idiom Blood is Thicker than Water. It means that people who have shed blood together in the battlefield (blood of the covenant) have a stronger bond than familial ties (water of the womb) which is quite the opposite of the latter - more popular saying.