13 My Lord said: Because that people has approached [Me] with its mouth And honored Me with its lips, But has kept its heart far from Me, And its worship of Me has been A commandment of men, learned by rote—
va-YO-mer a-do-NAI YA-an KEE ni-GASH ha-AM ha-ZEH b’-FEEV u-vis-fa-TAV ki-b’-DU-nee v’-li-BO ri-KHAK mi-ME-nee va-t’-HEE yir-a-TAM o-TEE mitz-VAT a-na-SHEEM m’-lu-ma-DAH
יג וַיֹּאמֶר אֲדֹנָי יַעַן כִּי נִגַּשׁ הָעָם הַזֶּה בְּפִיו וּבִשְׂפָתָיו כִּבְּדוּנִי וְלִבּוֹ רִחַק מִמֶּנִּי וַתְּהִי יִרְאָתָם אֹתִי מִצְוַת אֲנָשִׁים מְלֻמָּדָה׃
29:13 And its worship of Me has been a commandment of men, learned by rote
For what sin did God punish Yehuda? Compared to Shomron, the northern kingdom, with all its idolatries and immoralities, Yehuda seemed positively pious. In fact, they had purified their country under Chizkiyahu. Yeshayahu answers with one sentence. Though the people prayed and performed the ritual commandments, their service was not genuine, but only lip-service. Some commentators understood this as hypocrisy; however others interpret Yeshayahu’s description in a more literal sense — unfeeling, robotic observance that has no value. Hashem wants both our consistent external actions with corresponding internal feelings united in His service.