Likutei Moharan 8:6/ליקוטי מוהר"ן ח׳:ו׳

16. To achieve this, to be able to distinguish, separate and eliminate the bad from the good, one must engage in Torah and prayer. This Torah study should be delving into the depths of the law (Megillah 4b) —i.e., studying the Codifiers. For good and bad have a hold on the Torah. They are attached through the aspects of forbidden and permitted, impure and pure, kosher and unkosher, which appear in the Torah. And as long as one does not clarify the law, he is a mixture of good and bad.

2This is why he cannot separate and eliminate the bad from the good. He is in the aspect of (Proverbs 11:27), “He who seeks bad, it will come to him.” Only once he delves into and clarifies the law in practice, and determines <the permitted, the kosher and the pure>—i.e., by studying the Codifiers—can he separate <the bad from the good> (cf. Tikkuney Zohar #50, p.98b). However, being worthy of the intellect necessary for “delving into the depths of the law” only comes through prayer, because it is from there that intellect is drawn.