Mishnà su Deuteronomio 12:11

Rabbi Hanina, the vice-high priest said: pray for the welfare of the government, for were it not for the fear it inspires, every man would swallow his neighbor alive. R. Hananiah ben Teradion said: if two sit together and there are no words of Torah [spoken] between them, then this is a session of scorners, as it is said: “nor sat he in the seat of the scornful…[rather, the teaching of the Lord is his delight]” (Psalms 1:1); but if two sit together and there are words of Torah [spoken] between them, then the Shekhinah abides among them, as it is said: “then they that feared the Lord spoke one with another; and the Lord hearkened and heard, and a book of remembrance was written before Him, for them that feared the Lord and that thought upon His name” (Malachi 3:16). Now I have no [scriptural proof for the presence of the Shekhinah] except [among] two, how [do we know] that even one who sits and studies Torah the Holy One, blessed be He, fixes his reward? As it is said: “though he sit alone and [meditate] in stillness, yet he takes [a reward] unto himself” (Lamentations 3:28).

Akavia ben Mahalalel testified concerning four things. They said to him: Akavia, retract these four things which you say, and we will make you the head of the court in Israel. He said to them: it is better for me to be called a fool all my days than that I should become [even] for one hour a wicked man before God; So they shouldn’t say: “he withdrew his opinions for the sake of power.” He used to pronounce impure the hair which has been left over [in leprosy], And green (yellow) blood (of vaginal discharge); But the Sages declared them clean. He used to permit the wool of a first-born animal which was blemished and which had fallen out and had been put in a niche, the first-born being slaughtered afterwards; But the sages forbid it. He used to say: a woman proselyte and a freed slave-woman are not made to drink of the bitter waters. But the Sages say: they are made to drink. They said to him: it happened in the case of Karkemith, a freed slave-woman who was in Jerusalem, that Shemaiah and Avtalion made her drink. He said to them: they made her drink an example (and not the real water). Whereupon they excommunicated him; and he died while he was under excommunication, and the court stoned his coffin. Rabbi Judah said: God forbid [that one should say] that Akavia was excommunicated; for the courtyard is never locked for any man in Israel who was equal to Avavia ben Mahalalel in wisdom and the fear of sin. But whom did they excommunicate? Eliezer the son of Hanoch who cast doubt against the laws concerning the purifying of the hands. And when he died the court sent and laid a stone on his coffin. This teaches that whoever is excommunicated and dies while under excommunication, his coffin is stoned.