TT #781 · Parashas Ki Seitzei · Seventh Aliyah · Passuk 25:15
A complete and just weight you shall have, a complete and just measure you shall have, that your days may be prolonged in the land that the Eternal your God is giving you.
Torah Temimah points to Sifrei / Bava Batra.
TT lemma: לְמַעַן יַאֲרִיכוּ יָמֶיךָ.
מִכָּאן אָמְרוּ חֲכָמִים: כָּל מִצְוָה שֶׁמַּתַּן שְׂכָרָהּ בְּצִדָּהּ אֵין בֵּית דִּין שֶׁל מַטָּה נֶעֱנָשִׁין עָלֶיהָ.
English: From here the Sages said: Any mitzvah whose reward is stated beside it — the earthly court is not punished for (failure to enforce) it.
On the daf / in context: Because the Torah itself states the reward of long life, the earthly court is not held responsible for enforcing this particular commandment with the same severity.
Derash on the consequence of a reward stated in the verse.
When the Torah states the reward next to a commandment, the earthly court is not liable for failing to enforce it.