וַיִּצְעֲק֥וּ בְנֵֽי־יִשְׂרָאֵ֖ל אֶל־יְהוָ֑ה כִּ֠י תְּשַׁ֨ע מֵא֤וֹת רֶֽכֶב־בַּרְזֶל֙ ל֔וֹ וְ֠הוּא לָחַ֞ץ אֶת־בְּנֵ֧י יִשְׂרָאֵ֛ל בְּחָזְקָ֖ה עֶשְׂרִ֥ים שָׁנָֽה׃ (ס)
以色列人向永恆者哀求，因為他有九百輛鐵戰車，他大力欺壓以色列人二十年。
Rashi
Oppressed the Bnei Yisroel intensely. R' Tanchuma expounded, through ridicule. Similarly, it is said, "Your remarks offend me intensely."2Malachi, 3:13. Vs. 14, 15 there define the offensive remarks as ridicule of the worship of Adonoy.
Metzudat David
it was because of the nine hundred chariots that they did not have the feeling of approaching them in battle stirring in their hears. they therefore cried out to Hashem in prayer