Isaiah 30:18 (NKJV)
18 Therefore the Lord will wait, that He may be gracious to you; And therefore He will be exalted, that He may have mercy on you. For the Lord is a God of justice; Blessed are all those who wait for Him.
The LORD longs to be gracious but He will only provide such grace to those who wait on Him. He must first be exalted, shown to be in fact LORD of all, so that His mercy will in fact be revealed to be gracious mercy.
"Thus verse 18...is the pivot on which the whole chapter turns...God is patient with his people still, no less than with rebel Judah of old or the prodigal in Jesus' parable. But such grace gives us no licence to become lax. Note carefully the words of the apostle: 'Do you presume upon the riches of his kindness and forbearance and patience? Do you not know that God's kindness is meant to lead you to repentance?' (Rom 2:4 RSV) To be given time to repent is a great mercy which should be grasped with profound gratitude." - Webb, p129.