The Gemara presents a parable of someone who boasted he could run three parasangs before horses in swamplands but grew weary after running only three mil before a pedestrian on dry land, illustrating through escalating comparisons that if such minor exertion exhausted him, greater feats would exhaust him far more; it applies this parable to Jeremiah's astonishment at God's reward to Nebuchadnezzar for running four paces in God's honor, teaching that the reward for the righteous patriarchs who ran before God like horses throughout their lives will be immeasurably greater, and that this demonstrates the power even of a minor mitzvah.
מָשָׁל לְאָדָם אֶחָד שֶׁאָמַר: יָכוֹל אֲנִי לָרוּץ שָׁלֹשׁ פַּרְסָאוֹת לִפְנֵי הַסּוּסִים בֵּין בִּצְעֵי הַמַּיִם. נִזְדַּמֵּן לוֹ רַגְלִי אֶחָד, רָץ לְפָנָיו שְׁלֹשָׁה מִילִין בַּיַּבָּשָׁה וְנִלְאָה. אָמְרוּ לוֹ: וּמָה לִפְנֵי רַגְלִי כָּךְ, לִפְנֵי הַסּוּסִים – עַל אַחַת כַּמָּה וְכַמָּה. וּמָה שְׁלֹשֶׁת מִילִין כָּךְ, שָׁלֹשׁ פַּרְסָאוֹת – עַל אַחַת כַּמָּה וְכַמָּה. וּמָה בַּיַּבָּשָׁה כָּךְ, בֵּין בִּצְעֵי הַמַּיִם – עַל אַחַת כַּמָּה וְכַמָּה. אַף אַתָּה: וּמָה בִּשְׂכַר אַרְבַּע פְּסִיעוֹת שֶׁשִּׁלַּמְתִּי לְאוֹתוֹ רָשָׁע, שֶׁרָץ אַחַר כְּבוֹדִי, אַתָּה תָּמֵיהַּ? כְּשֶׁאֲנִי מְשַׁלֵּם שָׂכָר לְאַבְרָהָם יִצְחָק וְיַעֲקֹב שֶׁרָצוּ לְפָנַי כְּסוּסִים – עַל אַחַת כַּמָּה וְכַמָּה! הַיְינוּ דִּכְתִיב: ״לַנְּבִאִים נִשְׁבַּר לִבִּי בְקִרְבִּי רָחֲפוּ כׇּל עַצְמֹתַי הָיִיתִי כְּאִישׁ שִׁכּוֹר וּכְגֶבֶר עֲבָרוֹ יָיִן מִפְּנֵי ה׳ וּמִפְּנֵי דִּבְרֵי קׇדְשׁוֹ״. רְהַט בָּתְרֵיהּ, כִּדְרָהֵיט אַרְבַּע פְּסִיעוֹת, אֲתָא גַּבְרִיאֵל וְאוֹקְמֵיהּ. אָמַר רַבִּי יוֹחָנָן: אִילְמָלֵא לֹא בָּא גַּבְרִיאֵל וְהֶעֱמִידוֹ, לֹא הָיָה תַּקָּנָה לְשׂוֹנְאֵיהֶם שֶׁל יִשְׂרָאֵל.
The Gemara interprets the verse according to its straightforward meaning. This is a parable of a person who said: I can run three parasangs before the horses in the swamplands. He encountered a pedestrian and ran before him for three mil on dry land and wearied. The people said to him: And if running before a pedestrian you grew so weary, then if you were to run before horses, all the more so would you become weary. And if after running three mil you grew so weary, then if you were to run three parasangs, four times that distance, all the more so would you become weary. And if after running on dry land you grew so weary, then if you were to run in the swamplands, all the more so would you become weary. The Gemara explains: So too, you, Jeremiah: And if with regard to the reward for four paces that I compensated that wicked person, Nebuchadnezzar, who ran in My honor, you are astonished at its magnitude, when I compensate Abraham, Isaac, and Jacob, who ran before Me like horses throughout their lives, all the more so will their reward be great. This teaches the potency of even a minor mitzva. That is the meaning of that which is written: “Concerning the prophets. My heart within me is broken; all my bones shake; I am like a drunken man and like a man whom wine has overcome, due to the Lord and due to His sacred words” (Jeremiah 23:9). Nebuchadnezzar pursued the messenger to take the letter from him and revise it. When he ran four paces, the angel Gabriel came and stopped his pursuit. Rabbi Yoḥanan says: If Gabriel had not come and stopped his pursuit there would have been no remedy for the enemies of the Jewish people, a euphemism for the Jewish people. Had Nebuchadnezzar succeeded in revising the letter, his reward would have been so great that he would have been able to destroy the Jewish people, as he desired.