Do not separate yourself from the community

[...] Hillel said: do not separate yourself from the community, Do not trust in yourself until the day of your death, Do not judge your fellow man until you have reached his place. Do not say something that cannot be understood, trusting that in the end it will be understood. Say not: ‘when I shall have leisure I shall study;’ perhaps you will not have leisure.

Likewise, the Sages taught in a baraita: When the Jewish people is immersed in distress, and one of them separates himself from the community and does not share their suffering, the two ministering angels who accompany a person come and place their hands on his head, and say: This man, so-and-so, who has separated himself from the community, let him not see the consolation of the community. A similar idea is taught in another baraita: When the community is immersed in suffering, a person may not say: I will go to my home and I will eat and drink, and peace be upon you, my soul. And if he does so, the verse says about him: “And behold joy and gladness, slaying oxen and killing sheep, eating flesh and drinking wine; let us eat and drink, for tomorrow we shall die” (Isaiah 22:13). And the prophecy continues with what is written afterward, in the following verse: “And the Lord of hosts revealed Himself in my ears: Surely this iniquity shall not be expiated by you until you die” (Isaiah 22:14). [...] Rather, a person should be distressed together with the community. As we found with Moses our teacher that he was distressed together with the community, as it is stated during the war with Amalek: “But Moses’ hands were heavy; and they took a stone, and put it under him, and he sat upon it” (Exodus 17:12). But didn’t Moses have one pillow or one cushion to sit upon?! why was he forced to sit on a rock? Rather, Moses said as follows: Since the Jewish people are immersed in suffering, I too will be with them in suffering, as much as I am able, although I am not participating in the fighting. The baraita adds: And anyone who is distressed together with the community will merit seeing the consolation of the community.

Hillel says: Do not separate yourself from the community: At the time when the community is involved with Torah [study] and with the commandments, it is the crown of all the worlds and the glory of all of His domain. As 'with many people' that are gathered to fulfill His commandment, it 'is the King's glory'; and [so] it is not fitting to separate from them, as it is stated (Deuteronomy 33:5), "And there is a King in Yeshurun with the gathering." And this is with a community that goes in the good path and gathers to do a commandment. But it is not fitting to attach oneself to a community that leans to the bad path and the deeds of which are corrupted. And one who separates from them, behold, he is praiseworthy. And about this Yirmiyahu the prophet, peace be upon him, stated (Jeremiah 9:1), "Oh, to be in the desert, at an encampment for wayfarers! Oh, to leave my people, to go away from them— for they are all adulterers, a band of rogues."

[...] The meaning of the saying "do not separate yourself from the community" is when a person says: "why should I worry about the public? I will take care of myself." Therefore he said this is wrong, since all of Israel are one unity, some materially and some spiritually. And just as the material, which is the body, need the soul, so too the soul needs the body. So don't separate yourself from them, but connect to them, and look kindly and mercifully at them, to bring them back to the good path.
You may say: "I'm not retiring from them, they're retiring from me and oppose me in everything!" That's why he goes on to say: "and don't believe in yourself." In other words, the reason they retire from you is due to your own sin. And although you know you aren't a sinner before God, don't believe in yourself. In other words, when you see yourself alone, separate from them, this is proof that your shouldn't believe in yourself. The phrase is "don't believe" and the proof is "that you are on your own." Since "when a person's ways please the Lord, even his enemies will be at peace with him" (Proverbs 16:7) but obviously you still aren't fixed.