Helaman 6:27

yea, that same being who did plot with Cain, that if he would murder his brother Abel, it should not be known unto the world. And he did plot with Cain and his followers, from that time forth.

This was the same being who worked with Cain. He told Cain that if he murdered his brother Abel, no one would know. He worked with Cain and his followers from then on.

The same being who conspired with Cain, promising that if he murdered his brother Abel, no one would ever know. He’s been plotting with Cain and his followers ever since.