Asalaam Alaikum
in order to understand this, let us remind ourselves of these verses from quran and hadith from authenitc sunnah thus it will become easy then, insha Allah.
Allah the mighty and sublime says in the quran,
But only one who comes to Allah with a sound heart [26:89]
it is narrated in sahih bukhari
Narrated An-Nu'man bin Bashir: (O people!) Beware! Every king has a Hima and the Hima of Allah on the earth is His illegal (forbidden) things. Beware! There is a piece of flesh in the body if it becomes good (reformed) the whole body becomes good but if it gets spoilt the whole body gets spoilt and that is the heart. [sahih al-bukhari 52]
various scholars have also mentioned the importance of having a pure heart as it is the reason behind all our actions. please keep in mind the context in which we are taking the word 'heart'. all our whims and desires are born from our heart, it is also the place where our faith is.
this is about the part the heart longs and desires in another translation the heart wishes and longs [to commit the ultimate haram of zina]
now let us remind ourselves of these verses in quran,
That Day, We will seal over their mouths, and their hands will speak to Us, and their feet will testify about what they used to earn. [36:65]
Until, when they reach it, their hearing and their eyes and their skins will testify against them of what they used to do. [41:20]
these are the verses that explain the private confirms that or denies it.
we understand and believe that our intentions as long as it remains in our hearts, not put into action or words it is forgiven. once such a thing is put into action, that part of the body will testify against us infront of out Rabb on the aakhirah.
Ibn Battaal (may Allaah have mercy on him) said: Looking and speaking are called zina because they invite one to true zina. Hence he said: “the private part confirms that or denies it.” [End quote from Fath al-Baari]
reference :
- essay on the heart by ibn taymiyyah
- diseases of the hearts and their cures by ibn taymiyyah
- purification of the soul by jamaal al din zarabozo
may Allah the mighty and sublime grant you mercy and guide you to the straight path.
Allah knows best.