Utterly Mad

In this particular case it was "The blood of the covenant is thicker than the water of the womb"
First explanation I heard was that it meant that the bonds you make in life can matter more than blood relations. I was talking with someone and they said it was a biblical thing though I forget their exact phrasing.

It basically means "If you are a monk, relatives mean nothing." but that is 8th century version, the other interpretation is better.