אמר רבי יוחנן מאי דכתיב (משלי כח:יד) "אשרי אדם מפחד תמיד ומקשה לבו יפול ברעה"?
אקמצא ובר קמצא חרוב ירושלים אתרנגולא ותרנגולתא חרוב טור מלכא אשקא דריספק חרוב ביתר
אקמצא ובר קמצא חרוב ירושלים. דההוא גברא דרחמיה קמצא ובעל דבביה בר קמצא עבד סעודתא אמר ליה לשמעיה זיל אייתי לי קמצא אזל אייתי ליה בר קמצא אתא אשכחיה דהוה יתיב אמר ליה מכדי ההוא גברא בעל דבבא דההוא גברא הוא מאי בעית הכא קום פוק אמר ליה הואיל ואתאי שבקן ויהיבנא לך דמי מה דאכילנא ושתינא
Apropos the war that led to the destruction of the Second Temple, the Gemara examines several aspects of the destruction of that Temple in greater detail: Rabbi Yoḥanan said: What is the meaning of that which is written: “Happy is the man who fears always, but he who hardens his heart shall fall into mischief” (Proverbs 28:14)?
Jerusalem was destroyed on account of Kamtza and bar Kamtza. The place known as the King’s Mountain was destroyed on account of a rooster and a hen. The city of Beitar was destroyed on account of a shaft from a chariot.
The Gemara explains: Jerusalem was destroyed on account of Kamtza and bar Kamtza. As there was a certain man whose friend was named Kamtza and whose enemy was named bar Kamtza. He once made a large feast and said to his servant: Go bring me my friend Kamtza. The servant went and mistakenly brought him his enemy bar Kamtza. The man who was hosting the feast came and found bar Kamtza sitting at the feast. The host said to bar Kamtza. That man is the enemy of that man, that is, you are my enemy. What then do you want here? Arise and leave. Bar Kamtza said to him: Since I have already come, let me stay and I will give you money for whatever I eat and drink.
אמר ליה לא אמר ליה יהיבנא לך דמי פלגא דסעודתיך אמר ליה לא אמר ליה יהיבנא לך דמי כולה סעודתיך א"ל לא נקטיה בידיה ואוקמיה ואפקיה אמר הואיל והוו יתבי רבנן ולא מחו ביה [ש"מ קא ניחא להו] איזיל איכול בהו קורצא בי מלכא אזל אמר ליה לקיסר מרדו בך יהודאי א"ל מי יימר א"ל שדר להו קורבנא חזית אי מקרבין ליה אזל שדר בידיה עגלא תלתא בהדי דקאתי שדא ביה מומא בניב שפתים ואמרי לה בדוקין שבעין דוכתא דלדידן הוה מומא ולדידהו לאו מומא הוא סבור רבנן לקרוביה משום שלום מלכות אמר להו רבי זכריה בן אבקולס יאמרו בעלי מומין קריבין לגבי מזבח סבור למיקטליה דלא ליזיל ולימא אמר להו רבי זכריה יאמרו מטיל מום בקדשים יהרג אמר רבי יוחנן ענוותנותו של רבי זכריה בן אבקולס החריבה את ביתנו ושרפה את היכלנו והגליתנו מארצנו
The host said to him: No. Bar Kamtza said to him: I will give you money for half of the feast. The host said to him: No. Bar Kamtza then said to him: I will give you money for the entire feast. The host said to him: No. Finally, the host took bar Kamtza by his hand, stood him up, and took him out. After having been cast out from the feast, bar Kamtza said to himself: Since the Sages were sitting there and did not protest the actions of the host, I will therefore go and inform against them to the king. He went and said to the emperor: The Jews have rebelled against you. The emperor said to him: Who says? Bar Kamtza said to him: Go and test them; send them an offering, and see whether they will sacrifice it. The emperor went and sent with him a choice three-year-old calf. While bar Kamtza was coming with the calf to the Temple, he made a blemish on the calf’s upper lip. And some say he made the blemish on its eyelids, a place where according to us, it is a blemish, but according to them, it is not a blemish. The Sages thought to sacrifice the animal as an offering due to the imperative to maintain peace with the government. Rabbi Zekharya ben Avkolas said to them: If the priests do that, people will say that blemished animals may be sacrificed as offerings on the altar. The Sages thought to kill him [Bar Kamtza] so that he would not go and speak against them. Rabbi Zekharya said to them: If you kill him, people will say that one who makes a blemish on sacrificial animals is to be killed. Rabbi Yoḥanan says: The excessive humility of Rabbi Zekharya ben Avkolas destroyed our Temple, burned our Sanctuary, and exiled us from our land.
Marcus Jastrow's Talmudic Dictionary entry for "kamtza"
Jeffrey Rubenstein, Talmudic Stories: Narrative Art, Composition, and Culture (1999) p. 148
“Moreover, a touch of humor perhaps attends the names Qamza and Bar Qamza, reminiscent of Tweedledum and Tweedledee. Unattested as a name elsewhere in rabbinic literature, the designation “Qamza” may relate to the didactic purposes of the storyteller. That qamtsa means “locust” in Aramaic, rendering the two characters Locust and Son of Locust, or Mr. Locust and Locust Junior, shades the playful tone with an intimation of looming troubles. Locusts possess destructive potential, invading suddently, swarming through fields, leaving desolation for miles. Starvation and death, motifs that emerge later in the story, typically follow the arrival of locusts. And when two locusts surface, more are sure to follow. Now the guests enjoy the food, drink, and gaiety of the banquet, but their state of plenty has been jeopardized by the advent of locusts.”