Charles H. Spurgeon on Psalms 86:16

O turn unto me. As though the face of God had been before averted in anger, the suppliant pleads for a return of conscious favour. One turn of God's face will turn all our darkness into day. And have mercy upon me, that is all he asks, for he is lowly in heart; that is all he wants, for mercy answereth all a sinner's needs. Give thy strength unto thy servant. Gird me with it that I may serve thee, guard me with it that I may not be overcome. When the Lord gives us his own strength we are sufficient for all emergencies, and have no cause to fear any adversaries. And save the son of thine handmaid. He meant that he was a home born servant of God. As the sons of slaves were their master's property by their birth, so he gloried in being the son of a woman who herself belonged to the Lord. What others might think a degrading illustration he uses with delight, to show how intensely he loved the Lord's service; and also as a reason why the Lord should interpose to rescue him, seeing that he was no newly purchased servant, but had been in the house from his very birth.