The story of Kayin and Hevel (Cain and Abel) is not only about the first murder that ever happened. It also gives us an insight into how to get our prayers to be answered. Kayin and Hevel each brought a karbon (offering) to G-d. Hevel brought the offering from the best he had, while Kayin did not. Hevel’s offering was accepted, while Kayin’s was not. To get our prayers to be answered, we need to give our best effort at davening properly.