Albert Barnes on Revelation 2:21

And I gave her space to repent of her fornication. Probably after some direct and solemn warning of the evil of her course. The error and sin had been of long standing, but he now resolved to bear with it no longer. It is true of almost every great sinner, that sufficient time is given for repentance, and that vengeance is delayed after crime is committed. But it cannot always be deferred, for the period must arrive when no reason shall exist for longer delay, and when punishment must come upon the offender.

And she repented not. As she did not do it; as she showed no disposition to abandon her course; as all plea of having had no time to repent would now be taken away, it was proper that he should rise in his anger and cut her down.

(e) "space" Rom 2:14 (f) "repented not" Rev 9:20