Talmud for Sanhedrin 6:2
הָיָה רָחוֹק מִבֵּית הַסְּקִילָה כְּעֶשֶׂר אַמּוֹת, אוֹמְרִים לוֹ הִתְוַדֵּה, שֶׁכֵּן דֶּרֶךְ הַמּוּמָתִין מִתְוַדִּין, שֶׁכָּל הַמִּתְוַדֶּה יֶשׁ לוֹ חֵלֶק לָעוֹלָם הַבָּא. שֶׁכֵּן מָצִינוּ בְעָכָן שֶׁאָמַר לוֹ יְהוֹשֻׁעַ, בְּנִי שִׂים נָא כָבוֹד לַה' אֱלֹהֵי יִשְׂרָאֵל וְתֶן לוֹ תוֹדָה וְגוֹ' וַיַּעַן עָכָן אֶת יְהוֹשֻׁעַ וַיֹּאמַר אָמְנָה אָנֹכִי חָטָאתִי לַה' אֱלֹהֵי יִשְׂרָאֵל וְכָזֹאת וְגוֹ' (יהושע ז). וּמִנַּיִן שֶׁכִּפֶּר לוֹ וִדּוּיוֹ, שֶׁנֶּאֱמַר (שם) וַיֹּאמֶר יְהוֹשֻׁעַ מֶה עֲכַרְתָּנוּ יַעְכָּרְךָ ה' בַּיּוֹם הַזֶּה. הַיּוֹם הַזֶּה אַתָּה עָכוּר, וְאִי אַתָּה עָכוּר לָעוֹלָם הַבָּא. וְאִם אֵינוֹ יוֹדֵעַ לְהִתְוַדּוֹת, אוֹמְרִים לוֹ, אֱמֹר תְּהֵא מִיתָתִי כַפָּרָה עַל כָּל עֲוֹנוֹתָי. רַבִּי יְהוּדָה אוֹמֵר, אִם הָיָה יוֹדֵעַ שֶׁהוּא מְזֻמָּם, אוֹמֵר תְּהֵא מִיתָתִי כַּפָּרָה עַל כָּל עֲוֹנוֹתַי חוּץ מֵעָוֹן זֶה. אָמְרוּ לוֹ, אִם כֵּן, יְהוּ כָל אָדָם אוֹמְרִים כָּךְ כְּדֵי לְנַקּוֹת אֶת עַצְמָן:
At a distance of ten cubits from the stoning site he is told: "Confess." [For when he is close to it, he might panic and not be able to confess.] For all who are to be put to death confess. For all who confess have a share in the world to come, viz., Achan, who was told by Joshua (Joshua 7:19): "My son, confer, now, glory upon the L rd, the G d of Israel, and make confession to Him [(And even though one is not executed by his own confession, the execution of Achan was dictated by the circumstances.)] …And Achan answered Joshua and said: 'In truth, I have sinned to the L rd, the G d of Israel and as thus and as thus have I done.'" [The Gemara explains that he misappropriated the spoils in the time of Moses.] And whence do we derive that his confession atoned for him? From (Ibid. 25): "And Joshua said: 'How you have sullied us! May the L rd sully you on this day!'" — you are sullied on this day, but not for the world to come. And if he does not know how to confess, he is told: "Say: 'Let my death be an atonement for all of my sins.'" R. Yehudah says: If he knows that he was falsely testified against, he says: "Let my death be an atonement for all of my transgressions except this one." This was countered: If so, all men (sentenced to death) will say this in order to acquit themselves [in the eyes of their fellows and thus come to discredit the judges and the witnesses. The halachah is not in accordance with R. Yehudah.]