'Brethren' in the Bible

For it is an intense joy to me when brethren come and bear witness to your fidelity to the truth--that you live in obedience to the truth.

My dear friend, you are acting faithfully in all your behaviour towards the brethren, even when they are strangers to you.

For this reason, if I come, I shall not forget his conduct, nor his idle and mischievous talk against us. And he does not stop there: he not only will not receive the brethren, but those who desire to do this he hinders, and excludes them from the Church.