They sowed wheat and reaped thorns
In the question: All labor will come to naught. Disappointment over effort that bears no fruit.
("Sow wheat and reap thorns, they will wither, they will not prosper, and you will be ashamed of your harvest because of the fierce anger of the Lord" - Jeremiah 12:13)
Translation
Expression (Hebrew)
זָרְעוּ חִטִּים וְקֹצִים קָצָרוּ
Definition (Hebrew)
בְּהַשְׁאָלָה: כָּל עֲמָלָם יָרַד לְטִמְיוֹן. אַכְזָבָה עַל מַאֲמָץ שֶׁלֹּא נָשָׂא פְּרִי.
("זָרְעוּ חִטִּים וְקֹצִים קָצָרוּ נֶחְלוּ לֹא יוֹעִלוּ וּבֹשׁוּ מִתְּבוּאֹתֵיכֶם מֵחֲרוֹן אַף ה'"- יִרְמְיָה יב יג)