John Gill Bible Commentary

And a mixed multitude went up also with them,.... Some of these were Egyptians, and some of other nations that had resided in Egypt, and who, on various accounts, might choose to go along with the children of Israel; some through intermarriages with them, being loath to part with their relations, see Lev 20:10, others on account of religion, being proselytes of righteousness, and others through worldly interest, the land of Egypt being by the plagues a most desolate place; and such wonders being wrought for the children of Israel, they saw they were a people that were the favourites of heaven, and judged it safest and best and most for their interest to keep with them; the Targum of Jonathan computes the number of those to be two hundred and forty myriads: and flocks and herds, even very much cattle; the greatest part of which must be supposed to belong to the children of Israel, whose cattle were not destroyed when those of the Egyptians were; and the rest might be the cattle of such who feared and regarded the word of God, and took their cattle into their houses at the time of the plague of hail, whereby they were preserved; and which might be an inducement to them to take their herds and their flocks, and go along with the children of Israel, see Exo 9:20.