Albert Barnes Commentary Exodus 10:23

"they saw not one another, neither rose any one from his place for three days: but all the children of Israel had light in their dwellings." — Exodus 10:23 (ASV)

Had light in their dwellings - The sandstorm, if that were the cause, might not have extended to the district of Goshen; but the expression clearly denotes a miraculous intervention, whether accomplished or not by natural agencies.