וַיְהִ֗י אַֽחֲרֵי֙ מ֣וֹת שָׁא֔וּל וְדָוִ֣ד שָׁ֔ב מֵהַכּ֖וֹת אֶת־הָעֲמָלֵ֑ק וַיֵּ֧שֶׁב דָּוִ֛ד בְּצִקְלָ֖ג יָמִ֥ים שְׁנָֽיִם׃
And it came to pass after the death of Saul, when David was returned from the slaughter of the Amalekites, and David had abode two days in Ziklag;
Rashi
רבים MANY must imply at least three days (cf. Rashi on Leviticus 15:25). From here they (the Rabbis) derived the law that the siege of a heathen city must not be commenced less than three days before the Sabbath, and it (this verse) teaches you that the opening up (the invitation to make) peace (v. 10) must be repeated two or three days, for so it states, (II Samuel 1:1) “And David abode two days (ימים שנים) in Ziklag” (Sifrei Devarim 200:4; Shabbat 19a). And Scripture is speaking here of a war which is not obligatory upon them (Sifrei Devarim 200:1).