Oh how great is thy goodness, which thou hast laid up for them that fear thee! Another transition. David turns from prayer to praise, and in the four next verses (Psalms 31:19-22) eulogizes the goodness and mercy and marvellous loving-kindness of God, who has wrought gloriously for his people in the past, and has further an ample store of mercies laid up for them in the future.
Which thou hast wrought for them that trust in thee before the sons of men! God had wrought his mercies for his own people, but in the sight of men generally, whether good or bad.