In his explanation of bulooghal maram from the chapter of tahara (purification), shaykh uthameen divides tahara into two major categories.
In an intangible sense:
Which is the purification of the soul and heart from shirk and other forms of spiritual cleansing. This includes cleansing of the heart from impure things; such as hypocrisy, envy and other reprehensible emotions.
This connotation of the word tahara is what is intended in the ayah:
أولئك الذين لم يرد الله أن يطهر قلوبهم
Those are the ones whose hearts Allah does not want to purify
The second purification is from tangible things:
This category is further subdivided into:
i) Purification from what occurrences break ones state of physical purity and ii) purification of ones body and outer garments from any impure substances.
i) As for purification of occurrences which break ones state of physical purity: It is either minor or major. For minor (such as passing wind or sleep) wudu is needed and for major (such as having martial relations or ejaculation) ghusul is needed.
With regards to purification from impure substances:
This includes cleansing of impure things from ones clothes and body.
There is however a notable difference between; cleaning oneself from impure substances and the purification that is needed from occurrences which nessecitate minor or major purification, and that difference is in the need for intention between the two. As for washing ones body or outer garments, then no intention is needed. On the contrary, actions which have been commanded (such as wudu, ghusul) an intention would be nessecary.
The shaykh then goes on to explain:
When the jurists of religious law use the word tahara, it is in a tangible sense. As for those who speak regarding creedal matters and the oneness of Allah, then the word tahara would conform to an intangible meaning. This form of tahara (intangible) is more important than the other (tangible), despite both of them holding an importance.
All of this would come under the chapter of tahara
*I have translated the pages in a manner which I have understood the text, rather than an ‘exact’ word for word translation.