The following section from the Zohar discusses what happened after the brothers pulled Joseph out of the pit into which they had thrown him and had sold him to a caravan of Ishmaelites. Reuven, the oldest brother, had secretly planned to return Joseph safely to his father, but he had to leave to attend to his father. When he returned and discovered that Joseph had been sold, he and his brothers decided to tell Jacob that Joseph had been killed by a wild animal

"They took Joseph's tunic, slaughtered a kid-goat and dipped the tunic in the blood…." (Gen. 37:31)

The Rabbis taught that they did this because the blood of a goat is similar to human blood. (Bereishit Rabbah 84:19) Now although the Rabbis' explanation is a proper one, come and see [a more insightful analysis demonstrating that] the Holy One, blessed be He, is meticulous with saintly tzadikim to a hair's breadth.

Jacob…had a similar feeling when they told him that they had found the blood-stained tunic….

Although Jacob had acted properly [in following his mother's directives to acquire Isaac's blessing, instead of Esau], nevertheless, because he brought a kid-goat [to deceive his father, he was held responsible for the consequences]. A goat is from the side of harsh judgments [the aspect of gevura], and so when Jacob used it to deceive his father Isaac, who is also from the same aspect, he was punished via the blood of another goat - that his sons presented him with. Thus, regarding Jacob it is written, "With the skins of a kid-goat she covered his arms and his smooth-skinned neck"(Gen. 27:16) [so that Isaac would assume that Jacob was Esau] , and therefore "they dipped the tunic in the blood [of a kid-goat]", and they presented Jacob with the tunic in order to deceive him.

Jacob caused "and Isaac trembled in great perplexity" (Gen. 27:33) [when he discovered that he was tricked and someone other than Esau received the blessings], and this brought about his own confusion: "Can you identify this? Is it your son's tunic or not?" [He recognized the tunic and said, 'My son's tunic. A savage beast has devoured him. Joseph has surely been torn to bits']. (Gen. 37:32-33)

Rabbi Chiya [continued with this theme]: Regarding Isaac [when he felt Jacob's goatskin-covered arms] the verse states, "Are you indeed my son Esau or not?" (Gen. 27:21). And therefore regarding Jacob the verse states, "Is it your son's tunic or not?" This is all because the Holy One, blessed be He, is meticulous with tzadikim to a hair's breadth.

Rabbi Yehudah added: because of the anguished perplexity that Jacob caused Isaac to feel, he too had a similar feeling when they told him that they had found the blood-stained tunic. Isaac asked, "Who - where [is the one]… whom I blessed" (Gen. 27:33), and so Jacob was punished with the same "where?" [when Joseph was lost and asked the whereabouts of his brothers] - "where are they pasturing"?(Gen. 37:16) [and it was when he found them that they decided to sell him].

All this is true even though the Holy One blessed be He agreed with those blessings.

[Zohar I p. 185b-186a; Translation and commentary by Moshe Miller. First published by Fiftieth Gate Publications and Seminars.]