מַר רַבִּי יוֹחָנָן: לִבָּן שֶׁל רִאשׁוֹנִים כְּפִתְחוֹ שֶׁל אוּלָם, וְשֶׁל אַחֲרוֹנִים כְּפִתְחוֹ שֶׁל הֵיכָל, וְאָנוּ — כִּמְלֹא נֶקֶב מַחַט סִידְקִית.

Similarly, Rabbi Yoḥanan said: The hearts, i.e., the wisdom, of the early Sages were like the doorway to the Entrance Hall of the Temple, which was twenty by forty cubits, and the hearts of the later Sages were like the doorway to the Sanctuary, which was ten by twenty cubits. And we, i.e., our hearts, are like the eye of a fine needle.

Shir Hashirim Rabbah 5:2:2

אָמַר הַקָּדוֹשׁ בָּרוּךְ הוּא לְיִשְׂרָאֵל, בָּנַי, פִּתְחוּ לִי פֶּתַח אֶחָד שֶׁל תְּשׁוּבָה כְּחֻדָּהּ שֶׁל מַחַט, וַאֲנִי פּוֹתֵחַ לָכֶם פְּתָחִים שֶׁיִּהְיוּ עֲגָלוֹת וּקְרוֹנִיּוֹת נִכְנָסוֹת בּוֹ.

The Holy One Blessed Be he says that Israel, my sons, open and opening of repentance like the point of a needle, and I will open up for you an entrance large enough for wagons and crates to pass through

We also say it in Tashlich:

רַב לְהוֹשִׁיעַ הָאֵר עֵינֵינוּ כַּאֲשֶׁר בְּגֹדֶל רַחֲמֶיךָ הִבְטַחְתָּנוּ פִּתְחוּ לִי פֶּתַח כְּחֻדּוֹ שֶׁל מַחַט וַאֲנִי אֶפְתַּח לָכֶם פֶּתַח כְּפִתְחוֹ שֶׁל אוּלָם…

This translates a little differently, it says that if you open up an opening like the point of a needle I will open up the opening like the entrance to the foyer, presumably of the Temple. Perhaps they're both related because in the Mishkon, the wagons held the equipment and the vessels of the Tabernacle. so perhaps, it is by deduction that the opening is as large as the opening to the temple. Even though, technically the Tabernacle had a different size opening than the temple.

 In any case, I draw your attention a beautiful detail. Most people Translate the phrase colloquially as eye of a needle, as is used in the context of our Gemara. However, the saying about repentance uses the phrase point of a needle. My friends, the point of a needle is even more narrow than the eye of a needle. So, G-d is requiring for repentance even the most minimal Point, even smaller than the eye of a needle, merely the point of a needle.

for Video Shiur click here to listen:  Psychology of the DAF Eruvin 53

Translations Courtesy of Sefaria