כֹּ֤ה אָמַר֙ יְהוָ֣ה צְבָא֔וֹת פָּקַ֕דְתִּי אֵ֛ת אֲשֶׁר־עָשָׂ֥ה עֲמָלֵ֖ק לְיִשְׂרָאֵ֑ל אֲשֶׁר־שָׂ֥ם לוֹ֙ בַּדֶּ֔רֶךְ בַּעֲלֹת֖וֹ מִמִּצְרָֽיִם׃
So hat gesprochen der Herr Zebaot: Ich habe dessen gedacht, was Amalek Israel getan, der ihm nachstellte auf dem Wege bei seinem Zuge aus Ägypten.
Bartenura
חל להיות י"ד בע"ש, עיירות ומוקפין חומה קורין בו ביום – There is no Megillah reading on Shabbat, as a [rabbinic] preventive measure lest he take it [the Megillah] in his hand and he removes it four cubits into the public domain. And if one were to postpone the reading until after Shabbat, it would be the sixteenth [of Adar], and the Biblical verse (Esther 9:27), said: “ ולא יעבור /in the manner prescribed [and at the proper time each year].” But even though wall-city dwellers read the Megillah on the fourteenth [of Adar] when the fifteenth [of Adar] occurs on Shabbat, nevertheless, we don’t read [the portion] (Exodus 17:8 and following): “Amalek came [and fought with Israel at Rephidim]…” other than on Shabbat which is the fifteenth day [of Adar], and we recite the Haftarah of (I Samuel 15:2-31): “[Thus said the LORD of Hosts:] I am exacting the penalty [for what Amalek did to Israel, for the assault he made upon them on the road, on their way up from Egypt (and following)].” And [further] we discuss and expound the laws of Purim on that Sabbath. And regarding the Festive Purim meal, there are those who say that we do it on the fourteenth day [of Adar] when for on it we read the Megillah; and there are those who say that we postpone it until after Shabbat. And this is implied in the Jerusalem Talmud, that the Festival Purim meal that occurs on Shabbat is postponed but not advanced [to an earlier date], and according to everyone, we don’t do it on Shabbat.
Bartenura
לכסדרן – to the order of the Haftarot/prophetic portions, for until here, we recite Haftarot that are an abstract of/a reflection of the four [special] Torah portions: The portion of Shekalim – “At years of age” (II Kings 12:1); the portion of Zakhor: “…I am exacting the penalty for what Amalek did to Israel…”(I Samuel 15:2 – though many customs today have the community read the entire chapter); the portion of Parah: “And I will sprinkle upon you purifying waters” (Ezekiel 36:15); the portion of HaHodesh: “On the first day of the first month” (Ezekiel 45:18). From here and onwards, he returns to recite the prophetic portion that is a reflection of the [Torah] portion of that day.
Rashi
The best of that which was to be destroyed. [רֵאשִׁית] meaning the best of the ,20 Perhaps by his statement Shaul was indicating to Shmuel that they examined the animals to ascertain that none were Amoleikite sorcerers who had changed themselves to appear as animals [See above verse 2].—Da’as Sofrimחֵרֶם and similarly, "the best of your corn,"21 Devarim 18:4. as it is stated, "when you set aside the finest part of it."22 Bamidbar 18:30. Targum Yonoson renders [רֵאשִׁית] 'before they banned it.'