זוהר ויקרא — דף לו ע”ב

As they continue on their way, the time for prayer arrives, and Rabbi Elazar and Rabbi Pinchas ben Yair dismount and pray. During the prayer, a snake wraps itself around the legs of Rabbi Pinchas's donkey, and the animal brays in pain. After the prayer, Rabbi Pinchas says that that day, being absorbed in Torah, he had led his donkey through an unclean place, and this is why his animal is now being punished. He addresses the snake and commands it to leave, and the snake comes loose and falls away piece by piece.<br />
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Rabbi Elazar wonders at how "meticulous" the Holy One, blessed be He, is with the righteous, and Rabbi Pinchas answers that the Holy One, blessed be He, "is meticulous with the righteous and watches over them, wishing to add holiness to their holiness." The snake was a messenger, just as the Holy One, blessed be He, has many messengers and carries out His mission even through the beasts of the field, and even by the hand of a gentile.<br />
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The question then arises whether this mission can also be carried out by the hand of an Israelite: a wicked man by the hand of a righteous one — yes; but a wicked man by the hand of another wicked Israelite — only "when he did not intend it," as it is written, "and one who did not lie in wait, but God caused it to come to his hand," in order to punish both of them.<br />
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An example is brought from a verse in Job: "and when He grants quiet, who can condemn?" and likewise "and when He hides His face, who can behold Him?" — and the ways of the Holy One, blessed be He, in this apply equally to the nations and to man, to the whole world and to each individual. When people's deeds are upright, the right hand of the Holy One, blessed be He, is aroused and the left is subdued; and when their deeds are not upright, the left is aroused, and all those who come from that side become messengers to do harm. Israel, even when not meritorious, always comes from the side of the right, and this is why the mission to punish is carried out by the hand of beasts and nations, and not by the hand of Israel itself. The passage concludes with the example of the concubine at Gibeah: the Holy One, blessed be He, did not want wicked Israelites to rise up against one another, and in the end only the righteous remained to carry out the matter in the true way.