Likutei Moharan, Part II 60:1/ליקוטי מוהר"ן·תנינא ס׳:א׳

1When there are wars in the world, reason dictates that there will be higher prices. This is because the curse of Kayin—“When you work the land, it will no longer yield its strength to you” (Genesis 4:12)—is precipitated by the bloodshed in the world. This curse was issued on account of bloodshed, for the earth must [respond] this way when blood is spilled. For rain is produced by the vapors that rise up from the earth, as it is written, “An eid (mist) rose up from the earth and watered the whole surface of the earth” (ibid. 2:6). From the vapors which rise up from the earth, rain is created.

2But when there are wars and bloodshed, the aforementioned vapors become spilled blood. This is as it is written, “and you caused [the blood of] the Children of Israel to stream forth by the sword at the time of EiDaM (their calamity)” (Ezekiel 35:5)—i.e., the aforementioned EiDiM (mists), through which there is bloodshed. The same is true of a number of nations: Egypt, Ammon and Moab. When [the seer] prophesied their downfall, it is stated there: “at the time of eidam”—the aforementioned concept of eidim, which brings to bloodshed.

3Therefore, whenever there are wars and bloodshed, the land gives its strength to there. The vapors which rise up from her become bloodshed, and so rain does not fall. This is because the rains are made from the vapors, but now the vapors have become something else—namely, bloodshed. This is as our Sages, of blessed memory, taught: In a time of rain, even armies cease [marching] (Taanit 8b). Thus, when it rains, the armies and wars are halted.