Shomyo (Invocation of the Buddhas Name) (称名)
Shomyo means the invocation of the name(s) of the Buddha and/or Bodhisattva. Shomyo especially means reciting Namu Amida butsu, which is the myogo (name) of Amida Buddha and signifies Homage to Amida Buddha. Sometimes Shomyo indicates that shobutsu (many buddhas) chant the name of Amida Buddha with admiration and praise (Shobutsu Shomyo is in the seventeenth of the forty-eight vows made by Amida Buddha). In Jodo (Pure Land) sect, Shomyo particularly means invoking the name of Amida Buddha (Namu Amida butsu). This name invoking is a Shojo no go (a Rightly Established Practice) in order to be reborn in the Pure Land.
Zendo (Shan-dao) read '乃至十念若不生者不取正覚' in the Hongan (the eighteenth of the Forty-eight Vows) made by Amida as ' If, when I attain Buddhahood, the sentient beings of the ten quarters say my Name even ten times but do not attain birth, may I not attain the supreme enlightenment,' and interpreted it as the vow of Shomyo ojo (literally, people's birth in the Pure Land by the power of Shomyo). Because Shomyo was the act that Amida vowed in the Hongan (the Original Vow), it was a Shojo no go (a Rightly Established Practice), he argued.
Ryonin, who perfected Ohara Shomyo (Buddhist liturgical chant of Ohara), also established Yuzu Nenbutsu (Yuzu means 'circulating,' and Nenbutsu means reciting the name of Amida) or Dai (large) Nenbutsu and preached, 'one's own recitation of the Nenbutsu influences all others and that other people's recitation of the Nenbutsu influences oneself, interacting to help bring about the Birth of all in the Pure Land.'
According to Honen, the reason why Amida tathagata chose the sole act, Shomyo, was that while other deeds were difficult and inferior, Shomyo was the easiest and best deed. Chanting for salvation was not about reflecting on achievements but, was seen to relate solely on the power of Buddha's name when used in prayer. Thus, it certainly is the Shojo no goin (the Rightly Established Cause).
Shinran explained, 'Faith is the proper cause of the birth in the Pure Land, and one invokes Amida's name in order to repay the benevolence of Amida Buddha.'
(It is called Shinjin shoin [Faith is the proper cause.], Shomyo hon [Invocation is to repay the benevolence.])
In a broader sense, Shomyo other than Namu Amida butsu include: Namu Shaka muni butsu (Sakyamuni or Buddha), Namu Kanzeon Bosatsu (Avalokitesvara or Kannon Bodhisattva), and Namu daishi henjo kongo (the posthumous name of Kukai). Other than Buddhism, one can find many descriptions about the belief that one can escape suffering and receive relief by invoking the names of gods and buddhas in the sacred books of Taoism.
(One can find something similar also in the Muslim world.)