Musar zu Schemot 12:36

This is the secret of "finding favour in the eyes of Egypt," something which happened to the Egyptians after their first-born were slain. They humbled themselves before the Israelites, and as a result the Israelites emptied Egypt of silver and gold (12,36). Pharaoh also eventually humbled himself, when he asked Moses to give him a blessing in 12,32. He said this because he had come to realise that Israel itself represented blessing, and that he could be included in the blessing that is bestowed upon Israel.