וְעַתָּה֙ הִתְעָ֣רֶב נָ֔א אֶת־אֲדֹנִ֖י אֶת־מֶ֣לֶךְ אַשּׁ֑וּר וְאֶתְּנָ֤ה לְךָ֙ אַלְפַּ֣יִם סוּסִ֔ים אִם־תּוּכַ֕ל לָ֥תֶת לְךָ֖ רֹכְבִ֥ים עֲלֵיהֶֽם׃
Rashi on II Kings
Provide a security. Glorify yourself over him; enter a wager on the condition that if you are able to supply riders for two thousand horses.16Ravshokei implied that Chizkiyohu did not even have enough riders for the two thousand horses, so surely he is unable to mount a rebellion.—Ralbag