יַ֣ד הָעֵדִ֞ים תִּֽהְיֶה־בּ֤וֹ בָרִאשֹׁנָה֙ לַהֲמִית֔וֹ וְיַ֥ד כׇּל־הָעָ֖ם בָּאַחֲרֹנָ֑ה וּבִֽעַרְתָּ֥ הָרָ֖ע מִקִּרְבֶּֽךָ׃
Let the hands of the witnesses be the first to put the condemned to death, followed by the hands of the rest of the people. Thus you will sweep out evil from your midst.
Torah Temimah points to Sifrei / Sanhedrin on the duty of the witnesses.
יד העדים וגו׳. צוה הקב״ה שיהיו העדים ממונין על הענין.
English: “The hand of the witnesses…” The Holy One, Blessed be He, commanded that the witnesses themselves be appointed over the matter.
The witnesses are not merely informants; they are given the first responsibility for carrying out the sentence they caused to be imposed.
Derash on the verse (Sifrei / Bavli) — not a formal named middah of the 13. The verse is read as placing the witnesses in charge of the opening act of the execution.
The witnesses who brought the testimony must themselves begin the execution; the rest of the people follow after them.