Three days' journey into the wilderness. This was the demand made from the first (Exodus 5:3) by Divine direction (Exodus 3:18). Its object was to secure the absence of Egyptians as witnesses. As he shall command us.
Compare Exodus 10:26, where Moses observes—"We know not with what we must serve the Lord until we come thither." Divine directions were expected as to the number and the selection of the victims.