Chabad.org — English translation + Rashi
Torah Temimah points to Shabbos 93a (unit 6; single primary locus per emergency Core plan).
E-Daf.com — Shabbos 93a
HebrewBooks / Shas PDF
English: It was taught: “In doing it” — the whole of it and not part of it; from here, two who carried a load into the public domain on Shabbos are exempt.
Complete act required for liability — joint partial performance of a single act does not generate individual chatas liability.
When two people together carry a load that neither could have carried alone, neither is liable for a private chatas (or for the corresponding Shabbos prohibition in the classic case). The verse requires that the actor perform the whole of the prohibited action, not merely a portion of a joint act.