613 Mitzvot
Negative Mitzvah 26
Not to prophesy in the name of idols

Devarim (Deuteronomy) 13:14[13]
Yatse’u anashim bney-Vliya’al mikirbecha vayadichu et-yoshvey iram lemor nelchah vena’avdah elohim acherim asher lo-yedatem.
Certain base fellows are gone out from the midst of you, and have drawn away the inhabitants of their city, saying, Let us go and serve other elohim, which you have not known;

Devarim (Deuteronomy) 18:20
Ach hanavi asher yazid ledaber davar bishmi et asher lo-tsivitiv ledaber va’asher yedaber beshem elohim acherim umet hanavi hahu.
 But the prophet, who shall speak a word presumptuously in my name, which I have not commanded him to speak, or who shall speak in the name of other elohim, that same prophet shall die.

At the beginning of this perek (chapter), we find the purpose of this mitzvah is to make sure that we are following YHVH.

Devarim 13:1-5
If there arise in the midst of you a prophet, or a dreamer of dreams, and he give you a sign or a wonder,  and the sign or the wonder come to pass, of which he spoke to you, saying, Let us go after other elohim, which you have not known, and let us serve them; you shall not listen to the words of that prophet, or to that dreamer of dreams: for YHVH your Elohim proves you, to know whether you love YHVH your Elohim with all your heart and with all your soul. You shall walk after YHVH your Elohim , and fear him, and keep his mitzvot, and obey his voice, and you shall serve him, and cleave to him. That prophet, or that dreamer of dreams, shall be put to death, because he has spoken rebellion against YHVH your Elohim, who brought you out of the land of Egypt, and redeemed you out of the house of bondage, to draw you aside out of the way which the YHVH your Elohim commanded you to walk in. So shall you put away the evil from the midst of you.

To prophesy in the name of other elohim is rebellion. In fact, rebellion is a form of idolatry.

1 (Sh'mu'el) Samuel 15:23  For rebellion is as the sin of witchcraft, and stubbornness is as idolatry and terafim. Because you have rejected the word of YHVH, he has also rejected you from being king.

Yeshua said, "Many false prophets will arise, and will lead many astray... For there will arise false messiahs, and false prophets, and they will show great signs and wonders, so as to lead astray, if possible, even the chosen ones." (Matthew 24:11,24).

2 Kefa (Peter) 2:1 But false prophets also arose among the people, as false teachers will also be among you, who will secretly bring in destructive heresies, denying even the Master who bought them, bringing on themselves swift destruction.

Many will tell me in that day, ‘Adoni, Adoni, didn’t we prophesy in your name, in your name cast out demons, and in your name do many mighty works?’ Then I will tell them, ‘I never knew you. Depart from me, you who work lawlessness.’ (Matthew 7:22-23)

This is an interesting passage, because even if we think we are prophesying in His name and ignore His Torah, we are in truth, not speaking His name.

For such men are false emissaries, deceitful workers, masquerading as Messiah’s emissaries. And no wonder, for even HaSatan masquerades as an angel of light. It is no great thing therefore if his servants also masquerade as servants of righteousness, whose end will be according to their works. (2 Corinthians 11:13-15)

Again, it is their works that give them away. Here we see the real source of false prophesy, hasatan.

Isaiah 8:20  Turn to the law and to the testimony! If they don’t speak according to this word, surely there is no morning for them.

And here is the key, we must stick to His Word when we prophesy.

Shalom v'brakhot
Moreh Chizkiyah Shlomo (Carl)

Be libi tzavanti imratecha le ma'an lo echta lach.
(Tehillim 119:11)