Thematic Bible: What preachers should do

Do you not know that those working in the sacrifices eat those things of the temple; and those serving the altar partake of the altar? So also the Lord has commanded those preaching the gospel to live of the gospel.

My little children, I write these things to you, in order that you may not sin. And if any one may sin, we have an Advocate with the Father, Jesus Christ the righteous: he is the expiator for our sins: and not ours only, but indeed for the whole world. And in this we know that we have known him, if we are keeping his commandments. read more.
The one saying, I have known him, and keeping not his commandments, is a liar, and the truth is not in him; but whosoever shall keep his word, truly the divine love of God has been made perfect in him. In this we know that we are in him. The one saying that he abides in him ought himself so to walk about, as he also did walk about.