Hebrews 3:9

Proved me - “As if they would have made an experiment how much it was possible for me to bear.” - Doddridge. The meaning is: “they put my patience to a thorough trial.”

And saw my works - That is, my miracles, or my interpositions in their behalf. They saw the wonders at the Red Sea, the descent on Mount Sinai, the supply of manna, etc., and yet while seeing those works they rebelled. Even while sinners look on the doings of God, and are surrounded by the proofs of his power and goodness, they rebel, and provoke him to anger. Men sin when God is filling their houses with plenty; when he opens his hand daily to supply their wants; when they behold the manifestations of his goodness on the sea and on the land; and even in the midst of all the blessings of redemption, they provoke him to wrath.

Forty years - The whole time during which they were passing from Egypt to the promised land. This may mean either that they saw his works forty years, or that they tempted him forty years. The sense is not materially affected whichever interpretation is preferred.