וְאֶת־מִ֞י דָּאַ֤גְתְּ וַתִּֽירְאִי֙ כִּ֣י תְכַזֵּ֔בִי וְאוֹתִי֙ לֹ֣א זָכַ֔רְתְּ לֹא־שַׂ֖מְתְּ עַל־לִבֵּ֑ךְ הֲלֹ֨א אֲנִ֤י מַחְשֶׁה֙ וּמֵ֣עֹלָ֔ם וְאוֹתִ֖י לֹ֥א תִירָֽאִי׃
And of whom hast thou been afraid and in fear, that thou wouldest fail? And as for Me, thou hast not remembered Me, nor laid it to thy heart. Have not I held My peace even of long time? Therefore thou fearest Me not.
Ibn Ezra on Isaiah
And of whom hast thou been afraid, etc. What hadst thou to fear from an enemy and to be afraid of him for, so as to lie, and not to think of me.
Rashi on Isaiah
that you failed Heb. תְּכַזֵּבִי, that you ceased to worship Me and you betrayed Me. Comp. (infra 58:11) “Whose water shall not fail (יְכַזְּבוּ).” Comp. also (Psalms 116:11) “Every man is a traitor (כֹּזֵב).” Falajjnc in O.F., to fail. Likewise, every expression of כָּזָב means one upon whom people rely, and he fails and betrays them.