Origins of the term "עולם השקר"

Question

What are the earliest sources referring to our world as "עולם השקר"?

Thank you

Answer 1

The terms עוֹלָם דְּשֶׁקֶר for this world and עוֹלָם דְּקוּשְׁטָא for the next world appear in Vayikra Rabba 26:7 (Samuel raised from the dead is speaking to Saul):

כַּד הֲוֵינָא גַּבָּךְ הֲוֵינָא בְּעוֹלָם דְּשֶׁקֶר, וַהֲוֵית שְׁמִיעַ מִנִי מִלִּין שִׁקְרִין דַּהֲוֵינָא דָחֵיל מִנָּךְ דְּלָא תִקְטֵילוּנְנִי, וְכַדּוּן דַּאֲנָא בְּעוֹלָם דְּקוּשְׁטָא לֵית אַתְּ שְׁמִיעַ מִנִּי אֶלָּא מִלִּין דִּקְשׁוֹט

When I was with you I was in the false world and you heard false things from me because I was afraid of you killing me ["someone better than you" will take your place as king]. Now that I am in the true world, you will hear from me nothing but truth [David will take your place as king].

Answer 2

While the phrasing is not identical, it's possible that Pesachim 50a (and Bava Basra 10b) is an early source for this idea. In this passage, the gemara mentions עוֹלָם הָפוּךְ, "inverted world", which seems to be the same concept:

וְרַבִּי יְהוֹשֻׁעַ בֶּן לֵוִי אָמַר: אֵלּוּ בְּנֵי אָדָם שֶׁיְּקָרִין הֵן בָּעוֹלָם הַזֶּה, וּקְפוּיִין הֵן לָעוֹלָם הַבָּא. כִּי הָא דְּרַב יוֹסֵף בְּרֵיהּ דְּרַבִּי יְהוֹשֻׁעַ בֶּן לֵוִי חֲלַשׁ וְאִיתְנְגִיד, כִּי הֲדַר, אֲמַר לֵיהּ אֲבוּהּ: מַאי חֲזֵית? אֲמַר לֵיהּ: עוֹלָם הָפוּךְ רָאִיתִי, עֶלְיוֹנִים לְמַטָּה, וְתַחְתּוֹנִים לְמַעְלָה. אָמַר לוֹ: בְּנִי, עוֹלָם בָּרוּר רָאִיתָ. וַאֲנַן הֵיכִי הָתָם? כִּי הֵיכִי דְּאִיתוּ אֲנַן הָכָא, הָכִי אִיתִינַן הָתָם. ‏

And Rabbi Yehoshua ben Levi said: These are people who are considered important [yekarim] in this world and unimportant [kefuyim] in the World-to-Come. This is like the incident involving Rav Yosef, son of Rabbi Yehoshua ben Levi, who became ill and was about to expire. When he returned to good health, his father said to him: What did you see when you were about to die? He said to him: I saw an inverted world. Those above, i.e., those who are considered important in this world, were below, insignificant, while those below, i.e., those who are insignificant in this world, were above. He said to him: My son, you have seen a clear world. The world you have seen is the true world, as in that world people’s standings befit them. Rabbi Yehoshua ben Levi asked: And where are we, the Torah scholars, there? Rav Yosef responded: Just as we are regarded here, so are we regarded there.

[Text and translation taken from Sefaria. The translation used is the William Davidson (Koren - Steinsaltz) edition. Italics added.]

For what it's worth, the Hebrew version of Rav Steinsaltz's commentary ad loc. reiterates the framing of "עולם האמת" as the opposite of our world, so this might be it.

אמר לו: בני, עולם ברור ראית. שהעולם שראית הוא הוא עולם האמת, ובו היחסים בין הבריות הם כראוי להם.‏

[Bold in original, italics added.]

I could not find the exact phrase "עולם השקר" or "עולם שקר" in the Talmud with a cursory search on Sefaria.