Prime Minister Binyamin Netanyahu took Shas chairman Eli Yishai with him to Cairo in an effort to use the moral authority of Yishai and Shas mentor Rabbi Ovadia Yosef to help sell the Israeli public an eventual deal for kidnapped soldier Gilad Schalit, sources close to Netanyahu and Yishai said on Sunday. Yishai has long been a proponent of paying a high price to redeem captives and has made a point of meeting with Hamas officials and former American president Jimmy Carter in an effort to advance Schalit's release. "Netanyahu didn't bring Yishai with him just to be nice to him," a Yishai associate said. "Bibi wants his kosher certification." Yishai brought Egyptian President Hosni Mubarak a letter from Yosef, with whom the Egyptian leader has been on good terms for many years. Yosef lived in Egypt from 1947 to 1950, where he was head of the Cairo beth din (rabbinical court) and deputy chief rabbi of Egypt. "It is clear to me that due to your stature and experience, the organizations that have not abandoned the sword would not leave you empty-handed and you can help expedite his release," Yosef wrote Mubarak. Yishai asked Mubarak to send to Schalit via Hamas a siddur and a book of Psalms from Yosef, with a special dedication and a blessing that he should be released soon. "With God's help, your salvation is near and we will be happy to see your dear face together with your dear family," the rabbi wrote. "Be strong and courageous because the Lord your God is with you wherever you go." Yishai, who only eats food under the supervision of Yosef's kosher certification, did not eat at the post-Ramadan meal he attended with Mubarak and Netanyahu. The prime minister ate fish. "Yishai has been to Egypt before and he didn't eat then, either," Yishai's spokesman said. "There are good relations between Mubarak and Shas. Mubarak understands completely and does not take it personally." A source close to Netanyahu added that the prime minister "would not do anything to insult Mubarak."