אספה עלימו רעות. אַחְבִּיר רָעָה עַל רָעָה, לְשׁוֹן "סְפוּ שָׁנָה עַל שָׁנָה" (ישעיהו כ"ט), "סְפוֹת הָרָוָה" (דברים כ"ט), "עֹלוֹתֵיכֶם סְפוּ עַל זִבְחֵיכֶם" (ירמיהו ז'). דָּ"אַ — אספה אֲכַלֶּה, כְּמוֹ "פֶּן תִּסָּפֶה" (בראשית י"ט): אספה עלימו רעות — This means, I will join evil to evil, אספה having the same meaning as in (Isaiah 29:1) “add ye (ספו) year to year”; (Deuteronomy 29:18) “in order to add (ספות) the drunkenness to the thirst”; (Jeremiah 7:21) “Add (ספו) your burnt offerings to your sacrifices”. — Another explanation of אספה: it means, “I will expend” (bring to an end so that there will be no more evils to bring upon them); similar to (Genesis 19:15) “lest thou be brought to an end (תספה).
חצי אכלה בם. כָּל חִצַּי אַשְׁלִים בָּהֶם, וּקְלָלָה זוֹ לְפִי הַפֻּרְעָנוּת לִבְרָכָה הִיא — חִצַּי כָּלִים וְהֵם אֵינָם כָּלִים (ספרי; סוטה ט'): חצי אכלה בם means all my arrows I will use to the full against them (i.e., there will be no arrows left). This curse according to the wording in which the punishment is expressed, implies a blessing: My arrows will come to an end, but they themselves will not come to an end (i.e. they will never be exterminated) (Sifrei Devarim 321:2; Sotah 9a).