Halakhah for Nahum 1:9

One does not decree two bans in one day, as it is written,¹Sanhedrin 45b. “I will not again curse anymore … neither will I again smite anymore” (Gen. 8:21). It is written in the Twelve Minor Prophets, in the book of Malachi (3:6) “For I, the Lord, change not” and near to it is written, “Ye are cursed with the curse” (Mal. 3:9) which has the numerical value of “ban.” And it is written “Trouble shall not rise up the second time” (Nah. 1:9). We do not decree a ban except during the day, for it is written “And cursed his day” (Job 3:1) “Cursed be the day” (Jer. 20:14).