Genesis 46:27

27. All the souls… threescore and ten It accorded with Hebrew spirit and custom to so frame a register of honoured names as to have them sum up a definite and significant number . So Matthew’s genealogy of our Lord is arranged into three groups of fourteen names each, (Matthew 1:17,) and yet this could be done only by omitting several important names . The compiler of this list of Jacob’s sons might, by another process equally correct, have made it number sixty-nine by omitting Jacob himself, or a lesser number by omitting some of the grandchildren, or have made it exceed seventy by adding the names of Jacob’s wives: he purposely arranged it so as to make it number seventy souls . The descendants of Noah, as registered in chap . 10, amount to seventy . The seventy elders of Israel (Numbers 11:16) and the seventy disciples chosen by Jesus (Luke 10:1) show a peculiar regard for this mystic number . It is not improbable that the arrangement of genealogical lists was made up to round numbers, and, where possible, to a sacred number, that the whole might be the more easily and correctly transmitted by oral tradition .