אִם־אָ֭מַרְתִּי אֲסַפְּרָ֥ה כְמ֑וֹ הִנֵּ֤ה ד֭וֹר בָּנֶ֣יךָ בָגָֽדְתִּי׃
Seandainya aku berkata: “Aku akan menceritakan semuanya seperti itu”, tentulah aku telah mengkhianati angkatan anak-anak-Mu.
Rashi
If I said, “I shall tell it as it is” Said Asaph, “If I said in my heart to tell everything as it is, all that His people say about this.”
Radak
If I have said it. This is the statement of Asaph or any righteous person in every generation. If I have said it, I will recount this accusation as they say, "Generation of your children, behold, I have been unfaithful to you." The word "behold" is used in both early and later contexts. If I have said it, I will recount it like the generation of your children, "Behold, I have been unfaithful to you," and many others have done so in similar circumstances.
Rashi
behold I have made the generation of Your children into traitors That is to say that I would make them into traitors and wicked men.