Exodus 9:20
He that feared the word of the LORD among the servants of Pharaoh made his servants and his cattle flee into the houses: He that feared the word of the LORD among the servants of Pharaoh made his servants and his cattle flee into the houses:
Before the hail came, advance warning was given to bring servants and cattle in from the field into houses and barns or they would die, giving all of Pharaoh's servants an opportunity to protect them, to submit to God, and to escape judgment. Those who feared, regarded, respected, and believed the word obeyed by gathering their servants and cattle indoors, while those who disregarded, disbelieved, and did not regard the word left theirs in the field. Those who left them out had hearts hardened like Pharaoh's.
Fearing God's word meant obedience springing from belief. The warning tested the exalted pride of the Egyptians and revealed whose hearts were really moved and affected by God's wonderful dealings for Israel, whom the Egyptians had despised and cruelly treated. In thus providing a way of escape for all who chose to act on the warning, God showed mercy in the midst of judgment and offered safety to those who believed and obeyed.
The plague was announced beforehand and demonstrated that the storm obeyed the God of the Hebrews, and afterward Pharaoh confessed that he and his people had acted wickedly. Even the king's stubbornness helped spread the knowledge of God, and many Egyptians gave themselves to His service. The only true safety for nations and individuals is obedience to the voice of God and standing on the side of truth and righteousness.