Likutei Moharan 88:2/ליקוטי מוהר"ן פ״ח:ב׳

12. But when the tzaddik is widely known <and not concealed by clouds, as explained above,> then the accusatory forces are aware of him and keep a careful watch over him. They prevent him from drawing down bounty.

2Thus the Holy One, blessed be He, motivates the heart of a different tzaddik to foment argument against him <and to accuse him of being false. As a result he is concealed by clouds and is able to> draw down bounty.

3This is a “dispute for the sake of Heaven” (Avot 5:20)—i.e., for the sake of the tzaddik, who is called shamayim (heaven) because he possesses love and fear. Hence it is for the sake of Shamayim, the love and fear, <so that he is concealed by clouds> and is able to prepare rain <for the earth>—i.e., bounty and blessing.