Praise for murderers, calls for revenge and mobilization of angry activists: This is how an extreme right-wing Israeli group uses WhatsApp to communicate among its members.

Records recently obtained by Mashable show that members of the group, “El-Yahud Revenge,” advocate vigilantism and violence in response to attacks on Israeli Jews.

"For every terror attack, we need to retaliate with a vendetta like the one done by our strong brothers who murdered Muhammad Abu-Khdeir," wrote one member of the group, referencing the Palestinian teenager who was bludgeoned and burned to death in June as revenge after the killing of three Israeli teens.

“We need to start to act and not just by talking in this group," wrote another member. "We shouldn’t be afraid of getting arrested."

People walk past graffiti reading 'Death to Arabs' as they inspect the damage on the aftermath of an arson attack that targeted first-grade classrooms at a Jewish-Arab school near the Arab neighborhood of Beit Safafa, in southern Jerusalem, on November 30, 2014. Image: AHMAD GHARABLI/AFP/Getty Images

Indeed, one member of the group, the well-known right-wing activist Bentzi Gopstein, was arrested Tuesday along with nine other members of his own organization, on charges of inciting violence and terror activity. (Gopstein refused to comment for this story.)

At a time of heightened tensions in Israel, hate groups of all stripes are becoming more troublesome. Last week, three members of Gopstein's group were indicted for allegedly torching an integrated Jewish-Arab school in Jerusalem, according to the Jerusalem Post.

Israeli troops fire tear gas at Palestinian protesters during clashes after the protest of the death of Palestinian Cabinet member Ziad Abu Ain outside the Ofer military prison, near the West Bank city of Ramallah, Saturday Dec. 13, 2014.

While it's not clear that Gopstein's arrest had anything to do with the WhatsApp chats, transcripts from the group shed light on the backchannel communications used by well-known anti-Arab activists.

The group, which was founded in late October, has a few dozen members so far, including prominent names like the former lawmaker Michael Ben-Ari and the rapper Yoav Eliasi. (Ben-Ari refused to comment on the group's activities and Eliasi did not return calls.)

The transcripts, which were given to Mashable by a member of the ​group who was uncomfortable with what he witnessed, comprise messages, photos and videos from mid-November — one the most tense and violent weeks in Jerusalem in recent years.

After two Palestinians attacked worshippers at a synagogue on Nov. 18 attack killing five people, the messages got especially heated. One member of the group wrote: “Enough! If demonstrations don’t help, start committing terror attacks in Arab places. Those scumbags. Smash them, cut them, burn them. If the police do nothing and the government do nothing — we will."

Another member wrote: “I hope one of us will reach the league of the really great ones like Goldstein," referencing Baruch Goldstein, who murdered 29 Palestinians in Hebron in 1994.

Messages in the group included rhyming slogans in Hebrew that roughly translates to, “a good Arab is a dead Arab — a cool Arab is an orphan Arab."

The WhatsApp group's name is a play on words: El-Yahud means Jewish in Arabic, and the group goes by the same name as a Facebook page which was created in late June, following the murder of Abu Khdeir and the three Jewish teenagers. In August, the page was temporarily shut down after complaints that it incited violence against Arabs. However, it recently resurfaced, though with more toned down content. Whether some of the same people are involved is unclear.

WhatsApp, a popular application now owned by Facebook, offers its users the ability to conduct chats in closed circles. The company did not respond to calls for comment.

Questions such as, “How do we create deterrence?” were also raised in the group and, in that case, the answer came fast: kill terrorists; arrest Israeli journalists. “No,” one member of the group replied. “You don’t arrest them. You execute them for betraying their people.”

Every so often, the group's administrator warned members to be careful with their messages. “Guys, let’s not forget: many are eyeing our group," read one warning — an assessment shared by some members of the group. As one person wrote: "If any of these text messages about revenge ends up with the police, then it’s a problem we really don’t need."

Some members specifically mentioned the department at the Israel Security Agency (Shin Bet) that aims to foil Jewish terrorism as their main concern. In the transcript, the immediate response to such warnings came in form of a familiar right-wing motto: "Mavet La’aravim" — "Death to the Arabs."

Other messages were less violent.

El-Yahud members appeared to initiate actions against the employment of Arabs by Jewish-owned businesses. The transcripts shows that one of the main targets was Rami Levi, a low-cost supermarket chain that employs Arabs. Members of the group were called to load shopping carts with products, get to the register, ask if the store employs Arabs and then abandon the place, leaving the full carts in the store.

In some cases, it was hard to discern the intent of the calls for action. “Strong, healthy guys who are not scared and want to be brave Jewish Zionists — contact me now!!! Even better if you have a car and a driving license,” read one message.

When a member of the group found out that an Arab member of the Israeli parliament was staying in the southern city of Eilat, the message read: “The terrorist Ahmad Tibi is now in Herods hotel in Eilat. It’s about time we will change his vacation schedule." It was unclear what his call was for — or whether anyone heeded it.