Musar zu Schemuel II 7:18

But when the righteous man attains great honor he says, as did King David, of blessed memory, (II Samuel 7:18), “Who am I, O Lord God, and what is my house that Thou has brought me thus far?” The righteous man will continue and say, “Why has God caused me to merit all this good? For I have no good deeds, and I deserved to be oppressed and afflicted all my days because of my many sins. But the Creator has turned my evil into good, and with what can I repay Him even a little of what He deserves?” The righteous man will debate with himself and will say, “O my heart, my heart, do not trust in your great glory, for who knows if it is for your good or if this wealth is being guarded for someone else! Or do you know if night robbers will come and despoil you of all for which you have labored? Or do you know that God has given to you this glory because he rejects you, and if you have any merit whatever, he is rewarding you for it in this world in order that you go empty of merit in the world to come?”