If a carpet has urine on it and was wiped with a wet cloth and now is dry. Then someone writes with a pen or pointer on the carpet, will the nib of the pen now be impure? If it’s written in the book with that pen is the book also be najis on the place of writing.
بِسْمِ اللهِ الرَّحْمنِ الرَّحِيْم
In the name of Allah, the Most Gracious, the Most Merciful
If a carpet has urine on it, it will need to be washed in the following manner:
Pour water over the impure section of the carpet then dry the carpet with a clean sponge or cloth. You must ensure that the carpet dries at least to the extent that it does not drip water if you were to lift it up (This is for thick carpets that cannot be squeezed. If the carpet is thin and can be squeezed then it will be necessary to squeeze out the water after pouring water each time. When squeezing out the water for the third time, one must squeeze hard so that the water stops dripping).
Alternatively, you may use this method:
Estimate how much water would be needed to immerse the impure section of the carpet in a utensil. Thereafter, pour the estimated amount of water multiplied by three on the impure section of the carpet. For example, if you estimated that one liter of water would be needed to immerse the impure section of the carpet in a utensil, three liters of water will have to be poured over the impure section of the carpet. Doing this once will purify the carpet. You may then dry the carpet with a sponge or cloth.
If anything touched the place of urine after it has dried up, that thing will not become impure.
Only Allah alone knows best.
Answered by Maulana Imran Mughal
Checked and approved by Mufti Mohammed Tosir Miah
Darul Ifta Birmingham
Fatawa Hindiyyah(Beirut: DKI Publishers,2000), 48.
 At-Tahtawi, Hashiyah At-Tahtawi Ala Maraqi al-Falah (Beriut: DKI Publishers, 1997), 158.