Psalm 105:17 God had sent a man ahead of them—Joseph—who was sold as a slave.

Psalm 105 is a lengthy narrative about the people of God, and the many trials and experiences they had in Egypt. It includes their deliverance through the Red Sea, and the leadership of Moses. But long before Moses, long before the Red Sea crossing, God saved his people from starvation by sending Joseph into a place of plenty. His brothers badly used and abused him, but Joseph himself forgave them, and came to understand that it was God himself who had gone before him into Egypt. Wow.