Genesis 50:3
And forty days were fulfilled for him; for so are fulfilled the days of those which are embalmed: and the Egyptians mourned for him threescore and ten days. And forty days were fulfilled for him; for so are fulfilled the days of those which are embalmed: and the Egyptians mourned for him threescore and ten days.
The forty days were fulfilled for embalming, the customary period required for that work, and they belonged to Jacob's embalming. The Egyptians mourned for him threescore and ten days. That seventy days of mourning included the forty days used to embalm him. The same forty days for embalming and seventy days of Egyptian mourning are also read as Joseph's embalming and the mourning for him.
Embalming according to Egyptian custom, with its funeral processions and mourning practices, is confirmed by what is known of Egyptian history. The mourning and burial observances show the high regard paid to Jacob in Egypt. They reflect the impression the Israelites had made upon Egypt. The funeral obsequies show the care and respect of children for their father, with Joseph's care and sustenance of his father and the funeral march to a distant burial place, and illustrate honor to parents under the authority of the fifth commandment in the patriarchal household.