Three dynasties emerged from Abraham and are listed at the end of our parasha. Before Isaac’s birth he fathered Ishmael and after Sarah’s passing he fathered more children with Keturah, thus one dynasty emerged before Isaac and one after him. Sefat Emet compares these additional dynasties to the holiness that envelopes the Sabbath. Friday afternoon and Saturday night tie the Sabbath to the rest of the week. These touchpoints reshape our week and support the Sabbath. Similarly, these additional dynasties tie Isaac’s legacy and teaching to the rest of the world and in doing so provide a safe space for Isaac’s teaching.