Rom 16.17 Now I beseech you, brethren, mark them which cause divisions and offences contrary to the doctrine which ye have learned; and avoid them.
1Cor 5.9 I wrote unto you in an epistle not to company with fornicators:
2Tes 3.6-14 Now we command you, brethren, in the name of our Lord Jesus Christ, that ye withdraw yourselves from every brother that walketh disorderly, and not after the tradition which he received of us.