2 John 1:10

If there come any unto you
Under the character of a preacher;

and bring not this doctrine;
or does not preach the doctrine of Christ, as before explained, but despises it, and preaches a contrary one:

receive him not into [your] house;
neither into the house of God, suffer him not to preach there; nor into your own house, give him no entertainment there: false teachers always tried to creep into houses, where they served their own turn every way, both by feeding their bellies, and spreading their pernicious doctrines; and therefore such should: be avoided, both publicly and privately; their ministry should not be attended on in the church, or house of God; and they should not be entertained in private houses, and much less caressed:

neither bid him God speed;
or give him the usual civil form of salutation, as a good day to you, all hail, all health and prosperity attend you, the Lord be with you, and the like. The word used by the Jews was (rvya) , which signifies "happiness"; so it is said ^F9, what do they salute with? (rvya) , "God speed"; which was forbidden to say to one that was ploughing in the seventh year. The meaning is, that with such no familiar conversation should be had, lest any encouragement should be given them; or it should induce a suspicion in the minds of other saints, that they are in the same sentiments; or it should tend to make others think favourably of them, and be a snare and a stumblingblock to weak Christians.