An Israeli Political Aide Confided to His Rabbi. He Was Being Recorded.

Mr. Pfeffer, a yeshiva student once himself, noted that Judaism contains no confession-like guarantee of confidentiality, and said that if the rabbi indeed leaked the recording, he could have reasoned that he was acting for the “greater good” of Israel.

Only the onset of the Jewish Sabbath, during which religious Jews do not use the telephone, brought the frenzy of reporting to a standstill. Neither Mr. Haddad nor Rabbi Havura, the founder of a charity for pediatric cancer patients, could be reached for comment.

Mr. Bachar, the strategist, had in a year’s time helped Mr. Gantz, a career soldier but a political newcomer, create a new party, grow it into Israel’s largest and get it to within a few seats of clinching power.

Mr. Gantz called Mr. Bachar the victim of “a planned ambush,” and sought to focus outrage on Mr. Netanyahu, likening him to a gangster. “The mafia is here,” he wrote, showing a photo of the premier.

“Netanyahu has corrupted even the relationship of trust between a man and his rabbi,” Mr. Gantz wrote on Twitter. “Netanyahu, the pressure of your trial is reducing you to demeaning behavior even for you,” he added. “You’ve lost all inhibitions.”

Mr. Netanyahu’s party, Likud, said Mr. Bachar had been fired for telling the truth.

In a statement, Mr. Bachar did not specifically disavow his recorded remarks. He did praise Mr. Gantz as a “worthy leader” who had “greatly contributed” to strengthening Israel’s security “as a fighter, commander and chief of staff.”

Addressing the recording, he declined to go into detail, saying only that “the situation published is part of a campaign of fraud that has achieved a new record of humiliation.”