Albert Barnes Commentary Exodus 12:21

"Then Moses called for all the elders of Israel, and said unto them, Draw out, and take you lambs according to your families, and kill the passover." — Exodus 12:21 (ASV)

Draw out - that is, draw the lamb from the fold and then take it to the house.

The passover - The word is here applied to the lamb; an important fact, marking the lamb as the sign and pledge of the exemption of the Israelites.