What constitutes that by which purification is achieved using water?

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Purification is achieved by that which is pure water. Pure water is defined as that which is not impure (najis). The default understanding of the term 'purification' (tahara) in the speech of the Lawgiver or jurists refers to the legally defined meaning (shar'i) rather than the linguistic one. The term 'tahur' (that which purifies, with a damma on the ta) is the verbal noun (masdar). The term 'tahur' (with a fatha on the ta) is a transitive noun denoting something that purifies others, like a washing agent. This transitive nature is supported by the verse: {that He may purify you therewith} (Quran 8:11) and the Hadith where the Prophet (peace be upon him) stated, 'I have been given five things that no prophet before me was given; I was aided by terror cast into the hearts of the enemy for a month's journey, the earth was made a place of prostration and purification (tahura) for me.' (Agreed upon). If it only meant 'pure,' it would hold no distinction, as purity is for everyone. The question posed to the Prophet (peace be upon him) regarding ablution with seawater, to which he replied, 'Its water is tahur, and its dead things are lawful,' implies transitivity, as not everything pure is purifying.