Rebbe Moshe Leib of Sassov would exert tremendous effort to fulfill the mitzvah of pidyon shevuyim, redeeming a fellow Jew from captivity. He was once asked to undertake a journey to the house of a certain poritz (nobleman), the landlord of a Jew who had become poor and could not pay his rent. He had been imprisoned by this poritz, and R’ Moshe Leib undertook the long trip to bring payment and plead with the landlord to release the unfortunate man.
The trip took a number of days and Rebbe Moshe Leib could not obtain food with which to sustain himself, so he subsisted on nothing more than a few drinks of water. When he arrived at the nobleman’s mansion, exhausted and weak, he had to climb a long staircase to knock at the front door. By the time he entered, Rebbe Moshe Leib was literally starving, on the verge of collapse.
He was shown to the dining room, where he staggered in with his last vestige of strength, just as the servants were bringing in platters of gourmet food from which wafted tantalizing aromas, arousing his hunger even more. Rebbe Moshe Leib felt he could no longer endure the pangs of hunger, and knew that he was permitted to eat something because it was a case of pikuach nefesh (saving a life), as he might very well die of starvation. However, he was reluctant to eat something non-kosher, even if his life might depend on it.
Rebbe Moshe Leib solved his predicament and relieved his hunger pains in an unusual fashion: He began to say Nishmas, with the same fervor and devotion as when he recited it on Shabbos, savoring each word as though it were a delicious tidbit. The sweetness of the Nishmas prayer was sufficient to revive him and enabled him to refrain from eating the non-kosher food.
He succeeded in negotiating the release of the Jew from prison, and only then sought out nourishment for his body.