Morotomo ni iza to iwazu wa shide no yama koyu tomo kosamu mono naranaku ni - Gosen Wakashu(English Translation & Meaning)

もろともにいざと言はずは死出の山
越ゆとも越さむものならなくに

Roma-ji: Morotomo ni iza to iwazu wa shide no yama koyu tomo kosamu mono naranaku ni
English Translation: "Come, let us go on
together"—if you won't say so,
the Mountain of Death,
though you cross it, I would not
ever let you cross alone
Meaning: If you will not say, "Come, let us go together," then even should you cross the Mountain of Death, I would never let you cross it alone.
Commentary: Book Thirteen Love Poems V 962

Headnote: "Sent when he was secretly visiting the daughter of Kinyori Ason, and she fell ill and said she was sure to die."
The poet says that if she will not say, "Come, let us go together," then even should she cross the Mountain of Death, he would not let her cross alone. To a lover who speaks of dying, he tells her she should invite him to die with her, for he will not let her go alone, conveying his deep love.
According to the headnote, he was secretly visiting the daughter of Fujiwara no Kinyori when she fell ill and told him she would surely die, and he sent this. Kinyori also appears in the headnote of 942 in this book.
The poet, listed as "Asatada Ason," was Fujiwara no Asatada. A son of Fujiwara no Sadakata, the Sanjo Minister of the Right, he rose to Middle Counselor. One of the Thirty-Six Poetic Immortals, his "au koto no taete shi nakuba nakanaka ni" is included in the Ogura Hyakunin Isshu.

The first line, "Morotomo ni," means "together."
The second line, "iza to iwazu wa," means "if you will not say 'come,'" with "iza" a word of invitation and "zu wa" a negative supposition.
The third line, "shide no yama," means "the Mountain of Death," which the dead are said to cross on the way to the underworld.
The fourth line, "koyu tomo kosamu," means "though you cross it, would I let you," "kosu" meaning to let someone cross.
The last line, "mono naranaku ni," means "it is not so, after all," conveying his firm resolve not to let her cross alone.
Author: Fujiwara no Asatada
Source: Gosen Wakashu
Prev Poem: Ika ni shite kaku omou chō koto o dani hitozute narade kimi ni kataran
Next Poem: Kaku bakari fukaki iro ni mo utsurou o nao kimi kiku no hana to iwanan