Psalms 19:13

‘Keep back your servant also from presumptuous sins;

Let them not have dominion over me,

Then will I be upright,

And I will be clear from great transgression.'

Indeed he prays that God will keep him, as God's true servant, from sinning presumptuously. In context this surely means from deliberately disobeying His Instruction. That he does not want to do. Although he recognises that he does sin unwittingly, for he longs to be delivered from the dominion of sin, he wants to be delivered from a wayward heart. We can compare here Paul in Romans 7. It is the attitude of heart and mind that must be right, and then the rest will follow, depending on God's forgiveness and His activity within (12b, 13a).

It should be noted here that the Psalmist makes clear that his only hope is that God will act in His life. Without that he will have no hope of being true. It is in the end to God that he looks for deliverance.

And the result will be that he will be upright, and will be clear from ‘great transgression', the kind of sin that finally destroys, sin that is deliberate and habitual (see Numbers 15:30). Such sin ‘rules over' men (John 8:34; Romans 6:12) and results in judgment.

‘Presumptious', that is, ‘whatever is presumptious', whether sins or actions, which result from pride and arrogance, and are a deliberate flouting of God's law.