1 Corinthians 1:10

I beseech you, brethren, by the name of our Lord Jesus Christ, into whose one and the same fellowship, family, house, and Church we are all called, as many as are faithful and Christians, that ye all speak the same thing that is to say, that, like brothers, ye agree in words and in speech, and that ye all say at the same time "I am of Christ;" but let not one say, "I am of Paul," another, "I of Apollos." And, again, that ye agree not only in speech, but also in mind: otherwise your verbal confession would be feigned and false. Whence he adds as the root of concord:

That ye be perfectly joined together in the same mind and in the same judgment, that ye think the same think the same thing and agree among yourselves in Christ, that ye be fitly united to each other in one mind and spirit in Christ. For the Greek signifies, aptly and harmoniously to join and cement anything, so that the parts agree with each other and with the whole. And because a thing is then perfect and complete when it has in this way been neatly and harmoniously united, hence the word signifies also to perfect, as Psalms 8:2; 2 Corinthians 8:11. Be perfect, i.e., mutually agree amongst yourselves and with your Head; and Psalms 40:6 (Sept.).