That thou keep this commandment without spot, unrebukeable, until the appearing of our Lord Jesus Christ: That thou keep this commandment without spot - Two things are mentioned here:
1. That the commandment itself - the whole doctrine of Christ, should be kept entire.
2. That his life should be agreeable to that doctrine. Keep it without spot - let there be no blot on the sacred book; add nothing to it; take nothing from it; change nothing in it. Deliver down to thy successors the truth as thou hast had it from God himself.
Unrebukable - Let there be nothing in thy conduct or spirit contrary to this truth. Keep the truth, and the truth will keep thee.
Until the appearing of our Lord - Hand it down pure, and let thy conduct be a comment on it, that it may continue in the world and in the Church till the coming of Christ.