Question:
After Cain killed his brother Abel, The Name gave him a signal so they couldn’t kill him. I want to find out what signal he gave him.
Answer:
There are some interpretations:
The medraish says, that some say a horn rose in his forehead. And some say, a ‘zichus’ in which stood for him, and some say, one letter from the name of hashem was engraved in his forehead. And the ‘Maharshal’ explained a letter from Cain’s name (י’ ) to imply that he will live, meaning that he will not be killed, or given in the letter (ה) of the name of hashem.
And some say he was sentenced to the unsuscessful of all his origins:
And there are interpreters that say, that the signal in his heart, that is, to be strong and not to be afraid of being beaten by all his origins, and there he is shown in the heart of the animals and humans who come after him not to be burned.
Sources
See at genesis chapter 4 verse 16, and see there in Rashi and Rdak and in the
