The Talmud notes the general prohibition against eating before praying, deriving that one's physical needs should not take precedence over one's obligations to God.
אִם הִתְחִילוּ אֵין מַפְסִיקִין. נֵימָא תֶּיהְוֵי תְּיוּבְתָּא דְּרַבִּי יְהוֹשֻׁעַ בֶּן לֵוִי, דְּאָמַר רַבִּי יְהוֹשֻׁעַ בֶּן לֵוִי: כֵּיוָן שֶׁהִגִּיעַ זְמַן תְּפִלַּת הַמִּנְחָה, אָסוּר לְאָדָם שֶׁיִּטְעוֹם כְּלוּם קוֹדֶם שֶׁיִּתְפַּלֵּל תְּפִלַּת הַמִּנְחָה. לָא: לְעוֹלָם סָמוּךְ לְמִנְחָה גְּדוֹלָה — וּבְתִסְפּוֹרֶת בֶּן אֶלְעָשָׂה. וְלֹא לַמֶּרְחָץ — לְכוּלַּהּ מִילְּתָא דְּמֶרְחָץ. וְלֹא לְבוּרְסְקִי — לְבוּרְסְקִי גְּדוֹלָה. וְלֹא לֶאֱכוֹל — בִּסְעוּדָה גְּדוֹלָה. וְלֹא לָדִין — בִּתְחִלַּת דִּין. רַב אַחָא בַּר יַעֲקֹב אָמַר: לְעוֹלָם בְּתִסְפּוֹרֶת דִּידַן, לְכַתְּחִילָּה אַמַּאי לֹא יֵשֵׁב — גְּזֵירָה שֶׁמָּא יִשָּׁבֵר הַזּוּג. וְלֹא לַמֶּרְחָץ — לְהַזִּיעַ בְּעָלְמָא. לְכַתְּחִלָּה אַמַּאי לָא — גְּזֵירָה שֶׁמָּא יִתְעַלְּפֶה. וְלֹא לַבּוּרְסְקִי — לְעַיּוֹנֵי בְּעָלְמָא. לְכַתְּחִלָּה אַמַּאי לָא — דִּילְמָא חָזֵי פְּסֵידָא בִּזְבִינֵיהּ וּמִטְּרִיד. וְלֹא לֶאֱכוֹל — בִּסְעוּדָה קְטַנָּה. לְכַתְּחִלָּה אַמַּאי לָא — דִילְמָא אָתֵי לְאִמְּשׁוֹכֵי. וְלֹא לָדִין — בִּגְמַר הַדִּין. לְכַתְּחִלָּה אַמַּאי לָא — דִילְמָא חָזֵי טַעְמָא וְסָתַר דִּינָא.
The Gemara asks: In that case, if they started, they need not stop. Let us say that this will be a conclusive refutation of the opinion of Rabbi Yehoshua ben Levi, as Rabbi Yehoshua ben Levi said: Once the time of the afternoon prayer has arrived, it is prohibited for a person to taste anything before he recites the afternoon prayer. The implication is that even if one began to eat he must stop. Rather, that explanation is rejected and the Gemara says: Actually the mishna is referring to adjacent to minḥa gedola, and the statement of Rabbi Yehoshua ben Levi is dealing with adjacent to minḥa ketana. In response to the question: If the mishna means adjacent to minḥa gedola isn’t there significant time remaining in the day? The Gemara explains that each of the activities enumerated in the mishna is performed in an especially time-consuming manner. When the mishna said: A person may not sit before the barber, it was referring to a haircut of ben Elasa, whose haircut was very complicated and required several hours to complete. When the mishna said: A person may not go into the bathhouse adjacent to minḥa, it was referring to all matters involved in a visit to the bathhouse; not only washing, but also washing one’s hair, rinsing, and sweating. And he may not enter the tannery adjacent to minḥa, the reference is to a large tannery where there are many hides that require tanning and he must initiate the tanning process from the beginning. And he may not enter to eat, the reference is to a big meal, which lasts a long time. And he may not enter to sit in judgment, refers to a judge who enters at the beginning of the trial, and, generally, it will take a long time until a verdict is reached. Rav Aḥa bar Ya’akov said: Indeed the mishna can be explained as referring to minḥa gedola and actually, even our ordinary haircut is prohibited. Ab initio, why may he not sit before the barber adjacent to the time of minḥa? Due to a decree lest the scissors break, and considerable time pass until they repair the scissors or obtain others. When the mishna said: A person may not enter the bathhouse adjacent to minḥa, it is prohibited even if he is entering just to sweat. Ab initio, why may he not enter? Due to a decree issued by the Sages lest he faint in the bathhouse and considerable time elapse until he recovers. And he may not enter the tannery adjacent to minḥa, even if he intends just to examine the skins. Ab initio, why may he not enter? Due to the concern that perhaps he will notice damage to his merchandise and become anxious and come to restore what was ruined. And he may not enter to eat a meal adjacent to the time of minḥa is referring even to a small meal. Ab initio, why may he not enter? There is concern that perhaps he will come to extend his meal for a long time. And he may not enter to sit in judgment adjacent to the time of minḥa, the mishna is referring even at the conclusion of the trial. Ab initio, why may he not enter? Due to concern that perhaps he will find a reason, contrary to what he originally thought, and will overturn the verdict completely, necessitating the restart of the trial from the beginning.