Charles Ellicott Commentary Exodus 10:9

"And Moses said, We will go with our young and with our old; with our sons and with our daughters, with our flocks and with our herds will we go; for we must hold a feast unto Jehovah." — Exodus 10:9 (ASV)

With our sons and with our daughters ... for we must hold a feast. —It was customary in Egypt for children to join in festivals (Herod. ii. 60).

With our flocks and with our herds. —The family of Jacob brought numerous flocks and herds into Egypt (Genesis 47:1). These had, no doubt, increased, notwithstanding the oppression, and at the time of the Exodus must have been very numerous. The requirement to take a lamb for an house (Exodus 12:2) on the institution of the Passover involved the killing, on a single day, of 200,000 lambs. Even after this the flocks and herds which went out with them (Exodus 12:38) were very much cattle.