From the additional notes to The Treasury of David, Psalm 106, by Charles Spurgeon. This note relates to verse 7.
Provoking God imports an affront upon his longsuffering, and his patience. The movings of nature in the breasts of mankind, tell us how keenly, how regretfully, every man resents the abuse of his love; how hardly any prince, but one, can put up an offence against his acts of mercy; and how much more affrontive it is to despise majesty ruling by the golden sceptre of pardon, than by the iron rod of penal law. But now patience is a further and an higher advance of mercy; it is mercy drawn out at length; mercy wrestling with baseness, and striving, if possible, even to weary and outdo ingratitude; and therefore a sin against this is the highest pitch, the utmost improvement, and, as I may so speak, the ne plus ultra of provocation. For when patience shall come to be tired, and even out of breath with pardoning, let all the invention of mankind find something further, either upon which an offender may cast his hope, or against which he can commit a sin. But it was God's patience the ungrateful Israelites sinned against; for they even plied and pursued him with sin upon sin, one offence following and thronging upon the neck of another, the last account still rising highest, and swelling bigger, till the treasures of grace and pardon were so far drained and exhausted, that they provoked God to swear, and what is more, to swear in his wrath and with a full purpose of revenge, that they should never enter into his rest. Robert South.