In the Infinite Life Sutra, there is a Gatha (song) describing the Eighteenth Vow:

By the power of the Buddha’s primal vow,

All sentient beings who hear His Name and desire rebirth,

Will, without exception, reach His land,

And effortlessly dwell in the state of non-retrogression.

       “By the power of the Buddha’s primal vow,” means that the power of the fundamental vow enables beings to understand the need for rebirth, and consequently, “all who hear the Buddha’s Name” will desire to be reborn in His land.

       And they “will, without exception reach His land, and effortlessly dwell in the state of non-retrogression.” All will attain Buddhahood  and enjoy infinite light and infinite life identical to the Buddha’s. The Pure Land path is, therefore, an easy way without significant obstacles and requiring no meritorious assistance.

         The Gatha of rebirth is also called the Gatha that “ruptured hell.” There is an allusive story: 

       Around the time before the Tang Dynasty, there was a monk named Xuantong, who specialized in precepts. He was traveling and seeking consultations. One day he checked into a temple. During the night, he heard his neighbor recite aloud the Gatha of rebirth. He listened to their recitations a few times, never repeated it, and forgot about it.

        Later, after death, because he breached the precepts, he was brought down to hell to face the judgment of King Yama. The regal king of hells pounded his wooden bell with a striker and asked: “You were born in a country where the Buddha’s Dharma was propagated widely. If you have learned anything of Dharma, you may be seated high and present a lecture to us.” As Master Xuantong was stepping onto the high seat, he tried to recall things he had studied in life, but he could not think of any. Incredibly, he remembered this Gatha, and recited: “By the power of Amitabha Buddha’s fundamental vow, all sentient beings, who hear His Name and desire rebirth, will, without exception, reach His land, and effortlessly dwell in the state of non-retrogression.” 

      Good Heavens! As soon as he finished the recitation, King Yama bowed before him and said: “This Gatha you just recited praises the inconceivable merits and virtues of Amitabha Buddha in the Land of Ultimate Bliss. By this merit, you are now exempt from the punishment of hell. You may return to the human world and enjoy a long life.”

        The source of this Gatha’s power, which may free those who have fallen into hell, comes from the merits and virtues of Amitabha Buddha.

        In actuality, the overall merits and virtues of Amitabha Buddha are contained in his Six-character Name. We do not have to memorize this Gatha. In life, no matter how wise and how knowledgeable we are, when facing death, we may not remember things. What we may easily remember is “Namo Amitabha Buddha,” the deliverance of Buddha.

        Some people who have heard this story might think: “let me memorize well this Gatha in case I have to face Yama.” No such need! The Pure Land path not only exempts us from ever passing into the court of Yama—if we do, it would be most perilous—but has also won great respect from King Yama. Since we believe in and accept Amitabha Buddha’s deliverance, we will no longer be residents of the Saha world. We will be sagely members of the Land of Ultimate Bliss. We have the Dharma guardians of heavenly dragons and Buddhas of the ten directions, surrounding us, protecting us, and praising us.

        Master Xuantong freed himself from hell by reciting the Gatha. Had he recited the Six-character Name, he would have freed all the prisoners in hell.

(Translated by the Pure Land School Translation Team; 
edited by Householder Jingxin)