An angel once found Rav Kattina wearing a linen wrap, and he exclaimed, ‘Kattina, Kattina, a wrap in summer and a cloak in winter (apparently, neither of these had four corners, and so they were not obligated in tzitzit), and what is to happen to the law of tzitzit?’ ‘And do you punish’, asked Rav Kattina, ‘a person who neglects to perform a positive precept?’ ‘In a time of wrath’, replied the angel, ‘we do’.
The Maharal explains that the reason the Torah does not ordinarily mete out punishment for neglecting a positive commandment is because the person did not actually engage in inappropriate behavior, he merely missed an opportunity to reach the higher spiritual level offered by the mitzvah. In a “time of wrath,” however, a person is punished because of the lack of effort towards self-improvement.
The Maharsha suggests that during a “time of wrath” it is incumbent upon the religious leadership to strive to fulfill even more mitzvot that will serve as protection to the community. If they neglect to do so, they will be punished for their negligence.
Tosafot point out that the local Jewish courts have the ability to mete out punishments to people who do not perform positive commandments, and we can assume that Heavenly courts do as well. They argue, however, that that punishment only applies in cases where the individual is obligated in a mitzvah like sukkah or lulav and neglects to perform it. The case of tzitzit is different, because the obligation only exists if the person wears a four-cornered garment. It was not that Rav Kattina neglected the commandment; he was never obligated in the mitzvah, since he did not wear clothing that needed tzitzit.