Albert Barnes Commentary Exodus 5:3

"And they said, The God of the Hebrews hath met with us: let us go, we pray thee, three days` journey into the wilderness, and sacrifice unto Jehovah our God, lest he fall upon us with pestilence, or with the sword." — Exodus 5:3 (ASV)

Three days’ journey - See the (Exodus 3:18) note.

With pestilence, or with the sword - This shows that the plague was well known to the ancient Egyptians. The reference to the sword is equally natural, since the Israelites occupied the eastern district, which was frequently disturbed by the neighboring Shasous.