Mishnayos Brachos Perek 5 Mishnah 5

Concluding its discussion of the halakhot of prayer, the mishna discusses less practical aspects of prayer. One who prays and realizes that he erred in his prayer, it is a bad omen for him; it indicates to him that his prayer was not accepted. And if he who erred is the communal prayer leader, it is a bad omen for those who sent him, because a person’s agent has legal status equivalent to his own. On a similar note, they said about Rabbi Ḥanina ben Dosa that he would pray on behalf of the sick and immediately after his prayer he would say: This one shall recover from his illness and live and this one shall die. When they said to him: From where do you know? He said to them: If my prayer is fluent in my mouth as I recite it and there are no errors, I know that my prayer is accepted. And if not, I know that my prayer is rejected.

הַמִּתְפַּלֵּל וְטָעָה, סִימָן רַע לוֹ. וְאִם שְׁלִיחַ צִבּוּר הוּא, סִימָן רַע לְשׁוֹלְחָיו, מִפְּנֵי שֶׁשְּׁלוּחוֹ שֶׁל אָדָם כְּמוֹתוֹ. אָמְרוּ עָלָיו עַל רַבִּי חֲנִינָא בֶן דּוֹסָא, כְּשֶׁהָיָה מִתְפַּלֵּל עַל הַחוֹלִים וְאוֹמֵר, זֶה חַי וְזֶה מֵת. אָמְרוּ לוֹ, מִנַּיִן אַתָּה יוֹדֵעַ. אָמַר לָהֶם, אִם שְׁגוּרָה תְפִלָּתִי בְּפִי, יוֹדֵעַ אֲנִי שֶׁהוּא מְקֻבָּל. וְאִם לָאו, יוֹדֵעַ אֲנִי שֶׁהוּא מְטֹרָף: