Instead, he speaks to Abel, his brother. And then he kills him. But the text here is very strange, because it doesn't tell us what Cain says. In most biblical passages like this, the phrase would be followed by a quotation, a saying. But here there are no words, there is no quotation.
Some contemporary translations leave an empty space.
Cain can't speak to Abel any more than he can speak to God. Again, with our own children vividly before our eyes, we can see the story in a new way. We can see them refusing to face our own parental challenge. They refuse to encounter us. Instead, they take out their anger on each other, on someone weaker than an awesome parent.