Midrash for Isaiah 29:13

וַיֹּ֣אמֶר אֲדֹנָ֗י יַ֚עַן כִּ֤י נִגַּשׁ֙ הָעָ֣ם הַזֶּ֔ה בְּפִ֤יו וּבִשְׂפָתָיו֙ כִּבְּד֔וּנִי וְלִבּ֖וֹ רִחַ֣ק מִמֶּ֑נִּי וַתְּהִ֤י יִרְאָתָם֙ אֹתִ֔י מִצְוַ֥ת אֲנָשִׁ֖ים מְלֻמָּדָֽה׃

And the Lord said: Forasmuch as this people draw near, and with their mouth and with their lips do honour Me, But have removed their heart far from Me, And their fear of Me is a commandment of men learned by rote;

Tanna Debei Eliyahu Rabbah