'Brethren' in the Bible

In pointing out these things to the brethren, you will be a good servant of Christ Jesus, constantly nourished on the words of the faith and of the sound doctrine which you have been following.

Those who have believers as their masters must not be disrespectful to them because they are brethren, but must serve them all the more, because those who partake of the benefit are believers and beloved. Teach and preach these principles.