Isaiah 1:16, 17: Ourselves how can we purify

Ourselves how can we purify?
Thy word doth power convey,
And while we on Thy word rely.
We cast bur sins away;
From sinful acts our hands we cleanse,
The cursed thing remove,
Bring forth the fruits of penitence,
And wait Thy pardoning love.

Jesus, if Thou Thy power bestow,
From evil deeds we cease,
And learn in all the paths to go
Of legal righteousness:
But draw us on by hope and fear,
Till weary and oppress'd,
The reconciling word we hear,
And find the gospel-rest.