Midrasz do Rodzaju 47:4

"and he went down to Egypt": Lest you say he went down to receive the crown of kingdom; it is, therefore, written "vayagar sham": We are hereby apprised that he went down there only to sojourn ("lagur") there. And thus is it written (Bereshith 47:4) "And they said to Pharaoh: 'To sojourn in the land did we come. For there is no pasture for your servants' flocks. For the famine is sore in the land of Canaan. And now, let your servants abide in the land of Goshen.'" I might think, in great numbers; it is, therefore, written "in scant number," viz. (Devarim 10:22) "With seventy souls did your fathers go down to Egypt."