כֵּ֣ן יִֽהְיֶ֤ה דְבָרִי֙ אֲשֶׁ֣ר יֵצֵ֣א מִפִּ֔י לֹֽא־יָשׁ֥וּב אֵלַ֖י רֵיקָ֑ם כִּ֤י אִם־עָשָׂה֙ אֶת־אֲשֶׁ֣ר חָפַ֔צְתִּי וְהִצְלִ֖יחַ אֲשֶׁ֥ר שְׁלַחְתִּֽיו׃
Rashi on Isaiah
so shall be My word that emanates from My mouth to inform you through the prophets, will not return empty, but will do good to you if you heed them.
Ibn Ezra on Isaiah
So shall my word, etc. I shall fulfil all I spake to the prophets.