Charles H. Spurgeon on Psalms 71:2

In thy righteousness. The righteousness of God is in this place that virtue by which he makes good his promises —revenges injuries and rewards piety —which is elsewhere called his veracity. Upon this perfection David here calls, not because he was innocent before God, but because God had bound himself to him by promises, as if he were, in the presence of the men who were persecuting him, both innocent and righteous; and, therefore, worthy of being delivered from this last terrible calamity into which he has fallen through Absalom, since God had thus acted towards him. Hermann Venema.