וַיַּשְׁכֵּ֧ם שְׁמוּאֵ֛ל לִקְרַ֥את שָׁא֖וּל בַּבֹּ֑קֶר וַיֻּגַּ֨ד לִשְׁמוּאֵ֜ל לֵאמֹ֗ר בָּֽא־שָׁא֤וּל הַכַּרְמֶ֙לָה֙ וְהִנֵּ֨ה מַצִּ֥יב לוֹ֙ יָ֔ד וַיִּסֹּב֙ וַֽיַּעֲבֹ֔ר וַיֵּ֖רֶד הַגִּלְגָּֽל׃
Und Samuel stand früh auf, um Saul am Morgen zu treffen; und es wurde Samuel gesagt und gesagt:'Saul kam zu Karmel, und siehe, er errichtet ihm ein Denkmal und ist umhergegangen und weitergegangen und nach Gilgal hinuntergegangen.'
Sefer HaChinukh
The commandment to set up a place in which to defecate: That we were commanded that when our soldiers go out to war that we set up and designate a set place (see Tosefta Megillah 3:15) for the soldier, in which every man can go out to take care of his needs; so that their 'needs' not be [found] in very place and between the lodgings, like the [other] peoples do (Sanhedrin 104b). And about this it is stated (Deuteronomy 23:13), "And there shall be a yad for you outside the camp, etc." And the language of Sifrei is "A yad is always a place, as it states (I Samuel 15:12), 'and behold, he established a yad.'"