He made him eat gravel/ filled his mouth with gravel/ to crush someone/ to make him eat dirt (lit. gravel)
By metaphor: caused him trouble. Made him suffer. Or: subdued or silenced him (gravel signifies broken stones).
("Who gives man false bread, and after that fills his mouth with gravel" - Proverbs 20:17, and likewise: "And the sons of wrong shall no more speak perversely against us; for he shall fight our battles, and fill their mouth with gravel" - Abraham Mapu / The Painted Eagle, 11)
Translation
Expression (Hebrew)
הֶאֱכִיל אוֹתוֹ חָצָץ, מִלֵּא פִּיו חָצָץ
Definition (Hebrew)
בְּהַשְׁאָלָה:עָשָׂה לוֹ צָרוֹת. גָּרַם לוֹ לְסֵבֶל. אוֹ: הִכְנִיעַ אוֹ הִשְׁתִּיק אוֹתוֹ (חָצָץ מַשְׁמָע שִׁבְרֵי אֲבָנִים).
("עָרֵב לָאִישׁ לֶחֶם שָׁקֶר וְאַחַר יִמָּלֵא פִיהוּ חָצָץ"- מִשְׁלֵי כ יז, וְכֵן: "וְלֹא יֹסִיפוּ בְנֵי עַוְלָה לְדַבֵּר בָּנוּ סָרָה, כִּי הוּא יָרִיב אֶת יְרִיבֵינוּ וִימַלֵּא פִּיהֶם חָצָץ"- אַבְרָהָם מַאפּוּ/ עַיִט צָבוּעַ, 11 )