In John 5:42 Jesus stated:
ἀλλʼ ἔγνωκα ὑμᾶς ὅτι ⸉τὴν ἀγάπην τοῦ θεοῦ οὐκ ἔχετε⸊ ἐν ἑαυτοῖς (John 5:42, NA28)
But I know that you do not have the love of God within you. (John 5:42, ESV)
Why they recited in the Shema:
וְאָ֣הַבְתָּ֔ אֵ֖ת יְהוָ֣ה אֱלֹהֶ֑יךָ בְּכָל־לְבָבְךָ֥ (Deut. 6:5, MT)
You shall love the LORD your God with all your heart (Deut. 6:5, ESV)
What is particularly disturbing is ἐν ἑαυτοῖς (in yourselves) = בְּכָל־לְבָבְךָ֥ (in your heart) except כָל makes it with all your heart. Making this parallel, Jesus wasn't denying they had some love for God, but they were more concerned about how they looked to other people rather than loving God with all their hearts, souls, and strength. Jesus challenged human nature's ability to fulfill the Shema.
Jesus often attacked self-righteousness. His statement implied that reciting the Shema should challenge and convict rather than produce self-righteousness. Here's one song that has the idea:
My One Thing (1st two verses) Rich Mullins Everybody I know says they need just one thing And what they really mean is that they need just one thing more And everybody seems to think they've got it coming Well I know that I don't deserve You Still I want to love and serve You more and more You're my one thing Save me from those things that might distract me Please take them away and purify my heart I don't want to lose the eternal for the things that are passing Cause what will I have when the world is gone If it isn't for the love that goes on and on with ...