'Seal' in the Bible

And he received the sign of circumcision, a seal of the righteousness of the faith which he had yet being uncircumcised: that he might be the father of all them that believe, though they be not circumcised; that righteousness might be imputed unto them also:

So when I have completed this task and have put my seal on this contribution of theirs, I will visit you on my way to Spain.