Years earlier, Jacob's 20 year servitude to his father in-law in Haran was over and he left with his family and entourage. Along the way he hid his only daughter Dinah from an encounter that may have exposed him to marry her to his estranged brother Esau. Jacob was first intent on reaching Beit El, the place he had erected a monument (matzevah) as a covenant to build a House of God, but was delayed when Prince Shechem raped Dinah who bore Oesnat, the product of her rape. As a result Joseph's brothers Shimeon and Levi massacred 24000 men of Shechem.
On finally reaching Beit El, Jacob and his 11 sons built walls in Shalem (Jerusalem) on the high ridge above the Gihon Spring, but their effort was interrupted by the death of nurse Devorah, his mother Rivkah and the his wife Rachel as she gave birth to his 12th and final son Binyamin. After returning to Hevron, the brothers wanted to kill Oesnat to eradicate the painful memory, but Jacob insisted they don't. Instead Jacob placed Oesnat in a sneh (bush) in Midyan where she was cared for by the high priest and from where a midrashic source tells us she was miraculously transported to the House of Potifar in Egypt. After staying in Hevron, the home of Jacob's father, they eventually settled around Shechem where he had left his cattle and possessions and from where the string of tragedy continued.
Reuven had lost his birthright because of his interference in his father's affairs and Shimeon and Levi (the second and third sons) for their rebellion in Shechem; it fell to Yehuda the fourth son. The Biblical account of Joseph is interrupted by Yehuda’s encounter with Tamar because the ‘sweet spices’ allude to Oesnat. It turns out she was carried on the same caravan that collected and transported Joseph to Egypt. Many years after they arrived in Egypt, Pharaoh gave permission for Oesnat (of the House of Leah) to marry Joseph (of the House of Rachel). The marriage united both houses into the united tribes of Israel's (Jacob's) wives. From the marriage of Joseph and Oesnat the penultimate messianic root was born, the 'son of Joseph' preceded by the ultimate root, the 'son of David' from the marriage of Yehuda and Tamar.
Now we can understand why the section of Vayeishev in which Joseph and Oesnat are unified on their carriage to the House of Potifar in Egypt, is juxtaposed with the story of Yehuda and Tamar. Because, through the latter marriage comes the re-incarnate messianic root of Moshiach (Messiah) son of David. It’s from this point where the nation of Israel is ultimately unified to lead the world. Because of the marriage of Oesnat (the house of Leah) to Joseph (the house of Rachel) Jacob finally regained his happiness - and he lived! At this point he knew his descendants would eventually return from their exile, unified to fulfill his covenant to build the final and permanent Beit El, House of God, The Temple.
Now we can understand why the section of Vayeishev in which Joseph and Oesnat are unified on their carriage to the House of Potifar in Egypt, is juxtaposed with the story of Yehuda and Tamar. Because, through the latter marriage comes the re-incarnate messianic root of Moshiach (Messiah) son of David. It’s from this point where the nation of Israel is ultimately unified to lead the world. Because of the marriage of Oesnat (the house of Leah) to Joseph (the house of Rachel) Jacob finally regained his happiness - and he lived! At this point he knew his descendants would eventually return from their exile, unified to fulfill his covenant to build the final and permanent Beit El, House of God, The Temple.