וַיֹּאמְר֞וּ אִ֣ישׁ אֶל־רֵעֵ֗הוּ הָ֚בָה נִלְבְּנָ֣ה לְבֵנִ֔ים וְנִשְׂרְפָ֖ה לִשְׂרֵפָ֑ה וַתְּהִ֨י לָהֶ֤ם הַלְּבֵנָה֙ לְאָ֔בֶן וְהַ֣חֵמָ֔ר הָיָ֥ה לָהֶ֖ם לַחֹֽמֶר׃
Und sie sprachen einer zum andern. Wohlan, lasst uns Ziegel formen und sie brennen. Und die Ziegel dienten ihnen als Bausteine und das Erdharz als Mörtel.
Rashi on Genesis
איש אל רעהו ONE TO ANOTHER — One nation to the other: Mizraim to Cush, Cush to Put. and Put to Canaan (Genesis Rabbah 38:6).
Sforno on Genesis
הבה נלבנה לבנים, now they wanted to build permanent housing for themselves and pens for the flocks and herds. This was a common consensus, as we know from the Torah describing their speaking to each other as ויאמרו איש אלך רעהו, “they said each to his colleague.”
Radak on Genesis
ויאמרו..הבה, this word הבה, is customarily used in connection with a plan forming. It describes more a firm suggestion than a definite order, command. This is one of the reasons this word is always found in the feminine mode, and followed by a plural mode.