Reference: I’laam al-Mu’aasireen bi-Fataawa Ibn ‘Uthaymeen – Page 290
Question: What is your opinion regarding a man who is offered sincere advice, who then says “taqwa is here” and he points to his heart, quoting the statement of the Prophet (sal-Allaahu ‘alayhi wa sallam) and then he carries on sinning?
Response: This which some of the people do when they are offered sincere advice, they say: "taqwa is here" is (indeed) truthful speech, because the Prophet (sal-Allaahu ‘alayhi wa sallam) said:
«Taqwa is here» and he pointed to his chest; Saying it three times:
«Taqwa is here, Taqwa is here».
[Importantly], the one who said:
«Taqwa is here»
…[namely the Prophet (sal-Allaahu ‘alayhi wa sallam)] is also the one who said:
«In the body there is a piece of flesh which, if it is sound, the entire body will be sound, and if it is corrupt, the entire body will be corrupt. It is the heart»
…and based upon this, then apparent corruption is indicative of hidden corruption, so we say to the one who says:
«Taqwa is here»
…we say: If there is taqwa in that which is here [i.e. the heart], then that which we see from (your) apparent actions would also (indicate) taqwa; Because if the heart has taqwa, then it is imperative the parts of the body will too, as the Prophet (sal-Allaahu ‘alayhi wa sallam) said:
«…if it is sound, the entire body will be sound, and if it is corrupt, the entire body will be corrupt»
…and because of this, we demolish his argument and we say if (indeed) you were truthful that in your heart there is taqwa, then the parts of your body should also have taqwa (so you shouldn’t be sinning!).
 Taqwa – Fear, dread, awe. Piety to Allaah, fear of Allaah, warding off Allaah’s wrath, being conscious of Allaah, devotion, devoutness.