Sanhedrin11: 5
נְבִיא הַשֶּׁקֶר — הַמִּתְנַבֵּא עַל מַה שֶׁלֹּא שָׁמַע וּמַה שֶׁלֹּא נֶאֱמַר לוֹ; מִיתָתוֹ בִידֵי אָדָם. אֲבָל הַכּוֹבֵשׁ אֶת נְבוּאָתוֹ, וְהַמְוַתֵּר עַל דִּבְרֵי הַנָּבִיא, וְנָבִיא שֶׁעָבַר עַל דִּבְרֵי עַצְמוֹ — מִיתָתָן בִּידֵי שָׁמַיִם, שֶׁנֶּאֱמַר: ,,אָנֹכִי אֶדְרשׁ מֵעִמּוֹ”.
A false prophet —- [is] one who prophesies concerning that which he did not hear or that which was not said to him; he is executed at the hands of man. But one who suppresses his prophecy, and one who disregards the words of a prophet, and a prophet who transgresses his own words —- are executed at the hand of Heaven, as it is stated: I shall demand it from him.