Somagawa no asakarazu koso chigirishika nado kono kure o hikichigauran - Senzai Wakashu(English Translation & Meaning)

杣川の浅からずこそ契りしか
などこの暮れを引き違ふらん

Roma-ji: Somagawa no asakarazu koso chigirishika nado kono kure o hikichigauran
English Translation: Not shallow, like
the timber river, was the pledge
that we made together,
so why then this evening
should you draw it all awry?
Meaning: Our vows were deep as the timber-river is deep; why then, this very evening, should you go back on your word?
Commentary: Book Twelve Love Poems II 778

Headnote continued from the preceding poem: "Composed on the topic 'Love that breaks its promise as the hour arrives' at the courtiers' poetry contest at the Hōjūji Palace"
Composed at the same courtiers' contest at the Hōjūji Palace as the preceding poem, on the topic "Love that breaks its promise as the hour arrives." Our vow was not shallow, like the timber river, he says, so why do you break this evening's promise? Laying the depth of their vow upon the depth of the river where timber is floated, he reproaches the one who, after so deep a promise, breaks it when the evening comes.
The author, "Fujiwara no Morikata Ason," was the son of Fujiwara no Akitoki. He served as an official and was also known as a poet.
It is the second of three poems on the same topic, between the preceding poem, 777, and the next, 779. Following 744, 746 and 749 of this book, this poem too sings of a promise for "dusk."

First line, "somagawa no": "somagawa" is a river used to float timber cut in the logging hills, leading to "asakarazu," "not shallow," in the second line.
Second line, "asakarazu koso": "koso" is an emphatic particle binding with "shika" in the third line, "not shallow, as the timber river is not."
Third line, "chigirishika": "shika" is the perfective form of the past auxiliary "ki," concluding the "koso" of the second line. Because the sentence runs on after this koso construction, it takes an adversative sense, "though we pledged." The poem pauses here.
Fourth line, "nado kono kure o": "nado" is an interrogative adverb, "why this evening's promise." Like 744 and others in this book, it sings of "dusk."
Fifth line, "hikichigauran": "hikichigau" is to break a promise, with "hiki," "to pull," echoing the hauling of timber through "somagawa" in the first line. "Ran" is the auxiliary of conjecture on causes, "why should you break it?"
Author: Fujiwara no Morikata
Source: Senzai Wakashu
Prev Poem: Ima shibashi soradanome ni mo nagusamete omoitaenuru yoi no tamazusa
Next Poem: Omoiki ya shiji no hashigaki kakitsumete momoyo mo onaji marone sen to wa