Charles H. Spurgeon on Psalms 89:38

But thou hast cast off and abhorred. The Lord had promised not to cast off the seed of David, and yet it looked as if he had done so, and that too in the most angry manner, as if he loathed the person of the king. God's actions may appear to us to be the reverse of his promises, and then our best course is to come before him in prayer and put the matter before him just as it strikes our apprehension. We are allowed to do this, for this holy and inspired man did so unrebuked, but we must do it humbly and in faith. Thou hast been wroth with thine anointed. He deserved the wrath, doubtless, but the Psalmist's point is, that this appeared to him to conflict with the gracious covenant. He puts the matter plainly, and makes bold with the Lord, and the Lord loves to have his servants so do; it shows that they believe his engagements to be matters of fact.