Genesis 4:1-3

Now the man had relations with his wife Eve, and she conceived and gave birth to Cain, and she said, “I have obtained a male child with the help of the Lord.”

And again, she gave birth to his brother Abel. Now Abel was a keeper of flocks, but Cain was a cultivator of the ground.

So it came about in the course of time that Cain brought an offering to the Lord from the fruit of the ground.