Adam Clarke on Revelation 2:21

I gave her space to repent - "This alludes to the history of Jezebel. God first sent Elijah to Ahab to pronounce a severe judgment upon him; upon which Ahab showed tokens of repentance, and so God put off his punishment. By these means the like punishment pronounced against Jezebel was also put off. Thus God gave her time to repent, which she did not, but instead of that seduced her sons to the same sins. See 1 Kings 21:1-29. According to the Mosaical law, the punishment of idolatrous seducers was not to be delayed at all, but God sometimes showed mercy; and now much more under the Christian dispensation, though that mercy is often abused, and thus produces the contrary effect, as in the case of this Jezebel. See Ecc 8:11.