This passage, which is the original end of tractate Avot (Epstein, Introduction, 978), delivers a hope – but not a certainty – that Jerusalem will be rebuilt during “our days.” This conclusion of tractate Avot is articulated as a prayer formula that includes the phrase “May it be your will,” which is frequent in prayers (see for example, Mishnah Berakhot 9:3; Sifre Numbers 89, Kahana’s edition, p. 228). According to this prayer, God is the one who will build the city (see also Jerusalem Talmud, Berakhot 4:3, 8a; Taanit 2:2, 65c). Hope for an impending rebuilding of the Temple can also be found at the end of Mishnah Tamid 7:3:

 זה סדר התמיד לעבודת בית ייי אלהינו. שיבנה במהרה בימנו.

This is the order of the Tamid [sacrifice] for the service of the House of the Lord our God. May it be built speedily in our days (Kaufmann manuscript).

However, according to Jacob Epstein (Introduction, p. 979), the original end of Mishnah Tamid is “This is the order of the Tamid for the service of the House of the Lord our God,” while the prayer for a future rebuilding is a later addition. A similar addition – that, according to Epstein (Introduction, p. 686-687, 976), is tannaitic – was added to the end of tractate Taanit 4:8 (the same text also concludes tractate Taanit in the Jerusalem Talmud). All of these prayer formulas in the Mishnah were added to the ends of tractates in order to conclude them with a positive tone. Though it is not certain when these prayers were added to the Mishnah, it is clear that they articulate hopes rather than certainty regarding the immediate rebuilding of Jerusalem or the Temple.

Similar prayer formulas can be found in the Jerusalem Talmud, for example Berakhot 4:2, 7d:

…ותן חלקינו בתורתך עם עושי רצונך. בנה ביתך היכלך עירך ומקדשך במהרה בימנו.

And grant our portion in your Torah with those who do your will. Build your house (beytkha), your Sanctuary (heykhalkha), your city (‘irkha), and your Temple (miqdashkha) speedily in our days.

This passage – which appears as part of a prayer of the School of Rabbi Yannai for the one who wakes up from sleep – resembles the one in Mishnah Avot 5:20, for both ask for a rebuilding of the city “in our days” and a “portion in your Torah.” However, the order of the requests is different and the Jerusalem Talmud emphasizes the Temple itself with three additional words:  

In the Jerusalem Talmud, other prayer formulas for the rebuilding of Jerusalem articulate a certainty of a future rebuilding, but not necessarily an immediate one. Similarly, Berakhot 4:3, 8a; Taanit 2:2, 65c, in a prayer for the Ninth of Av, the day on which according to rabbinic tradition the Temple was destroyed: “For by fire you blazed [against] her, and by fire You will build her in the future.”Another formula which is found in Berakhot 4:3, 8a is:

...כי מפוזרים אתה מקבץ ותועים עליך לשפוט ועל הרשעים תשית ידך וישמחו כל חוסי בך בבניין עירך ובחידוש מקדשך...

For those who are scattered, You gather [them], and [for] those who go astray [it] is for You to judge [them], and upon the wicked You set your hand, and all who trust in you will rejoice at the rebuilding of your city (‘irkha) and in the restoration of your Temple (miqdashkha). 

This version is presented in the Jerusalem Talmud as part of the seven benedictions of the Amidah prayer. The Amidahis a central part of Jewish liturgy which includes eighteen benedictions on regular days, seven on Shabbat and festivals, and nine on Rosh Hashanah (the New Year). A request for a rebuilding of Jerusalem is attested in all. In ToseftaBerakhot 3:25 (MS. Vienna), this benediction is named: “Builder of Jerusalem” (“boneh yerushalem”) and so also in the Jerusalem Talmud (Berakhot 1:5, 3d and 2:3, 5a). The Tosefta does not provide the exact wording of this benediction.