From Owen on Psalm 130.
The proposal of repentance is a thing fitted and suited, in its own nature, to beget thoughts in the mind of a sinner that there is forgiveness with God. Repenting is for sinners only. ‘I came not,’ saith our Saviour, ‘to call the righteous, but sinners, to repentance.’ It is for them, and them only. …
O sinners, come and deal with God by repentance! Doth it not openly speak forgiveness in God? and, if it were otherwise, could men possibly be more frustrated or deceived? would not the institution of repentance be a lie? Such a delusion may proceed from Satan, but not from him who is the fountain of goodness, holiness, and truth.
His call to repentance is a full demonstration of his readiness to forgive. … God deceives none: whoever comes to him on his proposal of repentance shall find forgiveness. It is said of some, indeed, that he ‘will laugh at their calamity, and mock when their fear cometh.’ … But who are they? Only such as refuse his call to repentance.
From John Owen, Practical Exposition of Psalm 130, p203. What he’s saying here is more or less an expanded version of what it says in the Shorter Catechism – repentance involves among other things, some glimpse or apprehension of the mercy of God in Christ. Your conscience could tell you that you should turn from your sins, but it’s another thing to realise that there’s the possibility of turning from them to God. But the gospel call on sinners to repent is itself an assurance that salvation is available, that sinners can be reconciled to God, that ‘there is forgiveness with him,’ as Psalm 130 says.