Many people believe that it is necessary to walk forty steps with tissues or papers after urinating. Many are even seen counting their steps to forty. This is a misconception. Although walking with maintaining modesty could be necessary in personal cases to attain purity from urine, it has no relevance to the number forty.

There is tremendous emphasis on attaining purity from urine in the Hadith. Ibn Abbas (RA) said: The Messenger of Allah (SAW) passed by a garden in Madina, or Makkah. In the meantime, he heard the voices of two men who were being punished in their graves. The Messenger of Allah (SAW) said:

يُعَذَّبَانِ، وَمَا يُعَذَّبَانِ فِي كَبِيرٍ، ثُمَّ قَالَ: بَلَى، كَانَ أَحَدُهُمَا لَا يَسْتَبْرِئُ مِنْ بَوْلِهِ، وَكَانَ الْآخَرُيَمْشِي بِالنَّمِيمَةِ...
 

They are being punished. (Such) punishment is not caused by any great reason (from which it was very difficult to escape).
Then he said, yes, (but their major sins were) - one of them did not do 'Istibra' from urine, and another used to backbite. -Sunan-a- Nasa'i, Hadith 2068, 2069

According to the Hadith, Istibara, i.e., attaining purity from urine is necessary. In the Books of Fiqh, a level of 'Istibra' is discussed as follows:
طلب البراءة من الخارج بما تعارفه الإنسان من مشي أو تنحنح أو غيرهما إلى أن تنقطعالمادة.
 

'Istibra' is the act of taking measures according to one's habit to achieve purity from urine. For example, one should do such an amount of walking, clearing the throat, etc. that there is no chance of urine dropping again later.
See: al-Mawsu'atul Fiqhiyyah al-Quyatiyah, b. 4, p. 113; Raddul Muhtar, b. 1, p. 558

Therefore, in order to achieve purity from urine, a person should adopt any of these methods according to his convenience. If someone needs to walk (while maintaining modesty), he may do so to attain purity, but walking precisely 40 steps is not necessary.
(For more details on Istibra, read the article published in Alkawsar Dhil Hajj 1438 AH/September 2017 AH issue, 'Adabul Istinja : Evidence-Based Analysis of Two Issues', Mawlana Muhammad Imran.)

Translation: MD. Arif Billah