בַּבֹּ֤קֶר תֹּאמַר֙ מִֽי־יִתֵּ֣ן עֶ֔רֶב וּבָעֶ֥רֶב תֹּאמַ֖ר מִֽי־יִתֵּ֣ן בֹּ֑קֶר מִפַּ֤חַד לְבָֽבְךָ֙ אֲשֶׁ֣ר תִּפְחָ֔ד וּמִמַּרְאֵ֥ה עֵינֶ֖יךָ אֲשֶׁ֥ר תִּרְאֶֽה׃
Tu diras chaque matin: "Fût-ce encore hier soir!" Chaque soir tu diras:"Fût-ce encore ce matin!" Si horribles seront les transes de ton cœur et le spectacle qui frappera tes yeux.
Rashi
בבקר תאמר מי יתן ערב IN THE MORNING THOU SHALT SAY, WOULD IT WERE EVEN! — i.e. would that it were again yesterday evening,
Rashbam
מי יתן ערב, according to the plain meaning this refers to the following evening; this is the way the sick people react to their condition, assuming that they will start to get better by then.
Siftei Chakhamim
That it were last evening. Rashi is answering the question: Logic would dictate the opposite [of what the verse says], because it says in Bava Basra (16b), “When the sun is high, illness is relieved,” which indicates that illness is worse in the evening than in the morning! Regarding this he explains, “That it were last evening.”
Rashi
ובערב תאמר מי יתן בקר AND AT EVEN THOU SHALT SAY, WOULD IT WERE MORNING! — i.e. the morning of today, because the misery will constantly grow more severe, and the curse of each hour will be greater than that of the preceding (cf. Sotah 49a).