Comentário sobre Pirkei Avot 3:4

AND ONE WHO TURNS HIS MIND TO IDLE THINGS. Other versions have “and turns his mind,” which is what Rav had, as he writes: One who is up at night… and turns his mind… Midrash Shmuel, too, notes in discussing Rav’s commentary that he had “and turns his mind” as opposed to “and one who turns his mind.” He also writes in the name of Chasid Ya’avetz that the version “and one who turns his mind” is a typographical error that has crept into various editions. For “one who is up” must either be turning his mind to idle things or not. If he is, that is nothing more than the case of “one who turns his mind to idle things.” If he is not, then what is his sin? He concludes that there is no way to read this version of the mishna.
He writes in the name of Rashbam that “one who is up at night” could mean even in his home, and “one who is walking along the road” could be even during the day. In both cases he is alone, and the text does not read “one who is up at night alone.” And the danger is because mazikin might attack him. Based on Rashbam, we can properly read the version “and one who turns,” as we also can based on the words of R. Menachem Meiri quoted in Midrash Shmuel, but I am not going to go into this at length.
Maharal in Derech Chaim writes that this version is the main version, and explains that “one who stays up at night” will be damaged because “night was created only for sleeping or Torah study,” as the Talmud says in Eruvin 65a. The case of “one who turns his mind to idle things” refers even to one who does so during the day, meaning that he is drawn to idleness and seeks to remain idle. But “one who stays up at night,” even if he does not seek to remain idle, he “forfeits his life” unless he is sleeping, studying, or plying his trade—because any Torah that is not accompanied by a trade eventually turns to naught. Whereas if we have the version “and turns his mind,” we must resort to the forced explanation that the reason the mishna doesn’t simply say “and one who turns his mind to idle things at night” is that this would seem to include even someone who turns his mind to idle things in order to fall asleep.
Cf. my comments on mishna 8.

Rabbi Chananya ben Chakhinai says, etc. such a one is liable for [forfeiture of] his life: Since they are desirable times, he should only think during them about things that are desirable before the Omnipresent, may He be blessed. And those [things] are words of Torah. As how grand and desirable are these times for thinking about Torah, since he has no work to do and does not hear the voices of [other] people.

"And turns": And that is the textual variant of Rabbi Bartenura. And the version, "and the one that turns," is a mistake; as if so, "The one who stays awake" does not turn [to idleness], so why is he is liable [for his life]? And Rashbam, explained "One who stays awake" - and even at home; "and one who wanders on a road" - and even during the day; and about both of them, we are dealing [with him being] "alone." And according to his words, one can maintain the textual variant, "and one who turns." And see Tosafot Yom Tov.

"He who stays awake at night, and who wanders on a road alone": and thinks about idle things in his heart.

Introduction Rabbi Hananiah ben Hakinai was one of Rabbi Akiva’s students. According to legend he was also martyred.

and one who turns his heart to idleness, such a one is liable for [forfeiture of] his life: As he wastes a time in which he can have clear and correct thought, and diverts it from thoughts of Torah.

"this one is liable for [forfeiture of] his life": As night is the time of demons, and one who wanders on a road alone is in danger because of the brigands and several [other] bad occurrences; and if he had been thinking about words of Torah, it would have guarded him.

Rabbi Hananiah ben Hakinai said: one who wakes up at night, or walks on the way alone and turns his heart to idle matters, behold, this man is mortally guilty. One explanation for this statement is that nighttime is when demons are most active. So too, demons are especially present on the road. The person who wakes up at night or who walks alone on the road is vulnerable to these demons (demons are less likely to attack two). Therefore, if he is not engaged in the study of Torah, but rather in idle matters, he is liable to die. In other words, this is a physically dangerous act. [Many of us probably do not believe in demons. Nevertheless there may be some deep psychological truth to this statement. Waking up at night when no one else is around, or walking alone on a deserted path are times when a person is most likely to feel lonely and afraid. The antidote for such fears is Torah. Idle thoughts will only lead to more fear]. An alternative explanation for this statement is that these are golden opportunities to think about Torah. One who wastes his time thinking about idle matters when he could be learning Torah is, at least metaphorically speaking, mortally guilty. Maimonides actually teaches that the best time to learn, the time when a person is most likely to remember his studies, is at night. We should note that Maimonides followed his own advice and is known to have barely slept.