He commits sins and says, “Faith is in the heart”!
Question

Some people commit haram actions, such as shaving the beard and smoking, then if they are advised to stop doing that, they say: Faith is in the heart, not in growing a beard or giving up smoking. And they say: Allah does not look at your bodies; rather He looks at your heart. How should we respond to that?
Praise be to Allah.These words are often uttered by some ignorant or mistaken people. The words are true but are used in an incorrect manner, because the one who says that is trying to justify the sin that he is committing. He claims that faith in the heart is sufficient and there is no need to do righteous deeds and give up haram actions. This is an obvious mistake, because faith is not only in the heart; rather faith, as defined by Ahl as-Sunnah wa’l-Jamaa‘ah, is words on the lips, belief in the heart and physical actions.
Imam al-Hasan al-Basri (may Allah be pleased with him) said: Faith is not an outward display or wishful thinking; rather it is what settles in the heart and is confirmed by one’s actions.
Committing sins and refraining from doing righteous deeds is an indication that there is no faith in the heart, or that whatever faith is there is lacking. Allah, may He be exalted, says (interpretation of the meaning):
{O you who have believed, do not consume usury} [Aal ‘Imraan 3:130]
{O you who have believed, fear Allah and seek the means [of nearness] to Him and strive in His cause that you may succeed} [al-Maa’idah 5:35]
{those [among them] who believed in Allah and the Last Day and did righteousness} [al-Maa’idah 5:69]
{Indeed, those who believe and do righteous deeds } [al-Baqarah 2:277]
{those [among them] who believed in Allah and the Last Day and did righteousness } [al-Baqarah 2:62].
So faith cannot be called perfect faith unless it is accompanied by righteous deeds and giving up sin. Allah, may He be exalted, says (interpretation of the meaning):
{By time, 
Indeed, mankind is in loss, 
Except for those who have believed and done righteous deeds and advised each other to truth and advised each other to patience.} [al-‘Asr 103:1-3]
{O you who have believed, obey Allah and obey the Messenger} [an-Nisa’ 4:59]
{O you who have believed, respond to Allah and to the Messenger when he calls you to that which gives you life} [al-Anfaal 8:24].
So physical actions are not sufficient without faith in the heart, because that is the characteristic of the hypocrites, who will be in the lowest level of hell.
And faith in the heart is not sufficient without words on the lips and physical actions, because that is the way of the Murji’ah among the Jahamis and others, and it is a false path. Rather it is essential to have faith in the heart, words on the lips and physical actions. Committing sin indicates that the faith which is in the heart is weak and lacking, because faith increases by doing acts of worship and obedience (righteous deeds) and decreases by committing sin." (Al-Muntaqa min Fataawa ash-Shaykh Saalih al-Fawzaan  1/19).
The hadith referred to by that person who makes this argument – “… rather He looks at your hearts” – is narrated in Saheeh Muslim (2564) as follows: “Allah does not look at your (outward) forms and your wealth; rather He looks at your hearts and your deeds.” But it is a text which clearly indicates that what is required is both rectifying the heart and rectifying one’s deeds, and that one is enjoined to do both. So it is not permissible for a Muslim to fall short in doing righteous deeds or to commit haram actions and then say that Allah only looks at people’s hearts. Rather He looks at their hearts and their actions, and will bring them to account for what is in their hearts and for the deeds that they do.
And Allah knows best.