Halakhah for Sanhedrin 163:15
ויקם מתוך העדה ויקח רומח בידו מיכן שאין נכנסין בכלי זיין לבית המדרש שלף שננה והניחה באונקלו והיה
Now, what did he see? — Rab said: He saw what was happening and remembered the <i>halachah</i>, and said to him, 'O great-uncle! did you not teach us this on thy descent from Mount Sinai: He who cohabits with a heathen woman is punished by zealots?' He replied. 'He who reads the letter, let him be the agent [to carry out its instructions]'. Samuel said: He saw that 'There is no wisdom nor understanding nor counsel against the Lord':<span class="x" onmousemove="('comment',' Prov. XXI, 30. ');"><sup>27</sup></span> whenever the Divine Name is being profaned, honour must not be paid to one's teacher.<span class="x" onmousemove="('comment',' I.e., seeing the profanation of the Divine Name, he did not wait for Moses' ruling. ');"><sup>28</sup></span> R. Isaac said in R. Eleazar's name: He saw the angel wreaking destruction amongst the people. And he rose up out of the midst of the congregation, and took a spear in his hand;<span class="x" onmousemove="('comment',' Num. XXV, 7. ');"><sup>29</sup></span> hence one may not enter the house of learning with weapons.<span class="x" onmousemove="('comment',' Since he rose up out of the congregation, i.e., the Sanhedrin, implying that he went out. ');"><sup>30</sup></span> He removed its point and placed it in his undergarment, and went along