As occurs more often in Scripture, God’s deeds in the past are guarantees for his faithfulness in the future. The author has not remained quiet about God’s saving grace, as the Lord continues to care for him. He goes on to say, O Lord, you will not restrain your mercy from me.
How much David needs this in his royal office! God's steadfast love and faithfulness will always preserve him. This stands over against the lack of faith of God's people, also from the king-author himself.
He speaks of his strong trust, which is needed, considering what he tells further about all kinds of difficult circumstances. Psalms often show this alternation: thankfulness, complaint, redemption, then praise again. Psalm 50:23 reads, The one who offers thanksgiving as his sacrifice glorifies me; to one who orders his way rightly I will show the salvation of God!
11 As for you, O LORD, you will not restrain your mercy from me; your steadfast love and your faithfulness will ever preserve me!