Another interpretation: "If a man causes to be grazed over," and so on - to make him liable for this on its own and for that on its own [for the tooth and for the foot as separate liabilities]. "A field or vineyard": just as a vineyard has produce, so too the field has produce. "And he sends his animal": from here they said: if he handed his flock over to his bondman or to his agent, he is exempt. If he handed it to a deaf-mute, an imbecile, or a minor, he is liable. "And it grazes in another's field": Rabbi Nathan says: now consider one who stacks his grain within his fellow's field without permission, and the householder's animal goes out and damages it - I might apply to the owner the verse "and he sends his animal." Scripture therefore teaches, "in another's field" [the damage must occur in a field that is properly the other party's domain]. "The best of his field and the best of his vineyard" - of the one who caused the damage; these are the words of Rabbi Ishmael. Rabbi Akiva says: the verse comes to teach you that damages are assessed from the best land, and all the more so concerning consecrated property.
Sending the Beast Into Another's Field and Who Bears the Loss
Yalkut Shimoni on Torah 344:2
דָּבָר אַחֵר, כִּי יַבְעֶר וְגוֹ', לְחַיֵּב עַל זֶה בִּפְנֵי עַצְמוֹ וְעַל זֶה בִּפְנֵי עַצְמוֹ. שָׂדֶה אוֹ כֶרֶם, מַה כֶּרֶם יֵשׁ בּוֹ פֵּרוֹת אַף שָׂדֶה יֵשׁ בָּהּ פֵּרוֹת. וְשִׁלַּח אֶת בְּעִירֹה, מִכָּאן אָמְרוּ, אִם מָסַר צֹאנוֹ לְעַבְדּוֹ אוֹ לִשְׁלוּחוֹ, פָּטוּר. לְחֵרֵשׁ שׁוֹטֶה וְקָטָן, חַיָּב. וּבִעֵר בִּשְׂדֵה אַחֵר, רַבִּי נָתָן אוֹמֵר, וַהֲרֵי הַמַּגְדִּישׁ בְּתוֹךְ שְׂדֵה חֲבֵרוֹ שֶׁלֹּא בִּרְשׁוּת, וְיָצְאָה בְּהֶמְתּוֹ שֶׁל בַּעַל הַבַּיִת וְהִזִּיקָה, קוֹרֵא אֲנִי עָלָיו וְשִׁלַּח אֶת בְּעִירֹה, תַּלְמוּד לוֹמַר בִּשְׂדֵה אַחֵר. מֵיטַב שָׂדֵהוּ וּמֵיטַב כַּרְמוֹ, שֶׁל מַזִּיק, דִּבְרֵי רַבִּי יִשְׁמָעֵאל. רַבִּי עֲקִיבָא אוֹמֵר, בָּא הַכָּתוּב לְלַמֶּדְךָ שֶׁשָּׁמִין נְזָקִין בְּעִידִית, קַל וָחֹמֶר בְּהֶקְדֵּשׁ.