It is narrated from Sayyiduna Mughirah bin Shu’bah (may Allah be pleased with him) that the Messenger of Allah (peace and blessings be upon him) came riding on the horse of such-and-such people, then he spread both his legs and urinated while standing.
Hadith Referenceصحيح ابن خزيمه / جماع أبواب الآداب المحتاج إليها في إتيان الغائط والبول إلى الفراغ منها / 63
Hadith Gradingالألبانی:اسناده صحيح: سنن ابن ماجه: كتاب الطهارة: باب ماجاء فى البول قائما: 306
These ahadith are evidence that urinating while standing is permissible, provided that it is possible to avoid urine splashes. Despite this permissibility, urinating while sitting is preferable and superior, because sitting while urinating was your (the Prophet’s) constant practice, and in this there is greater protection from urine splashes. Furthermore, all the narrations that have been reported regarding the prohibition of urinating while standing are weak. It is narrated from Ibn Umar radi Allahu anhuma that Umar radi Allahu anhu stated:
«رَانِيرَسُولُاللهِ صلى الله عليه وسلم أبولُقَائِمًا،فَقَالَ: يا عُمَرُ ا لا تَبُلْقَائِمًا،فَمَابُلْتُقَائِمَابَعْدُ»
The Messenger of Allah sallallahu alayhi wa sallam saw me urinating while standing and said: “Umar! Do not urinate while standing.”
After that, I never urinated while standing.
[بيهقي: 102/1، ابن ماجه: 308، الضعيفه: 934]
Its chain is weak; Abdul Karim ibn Abu al-Mukhariq is a weak narrator. Rather, it is authentically established with a sahih chain that Umar radi Allahu anhu stated:
«مَابُلْتُقَائِمًامُنْذُأَسْلَمْتُ»
“After accepting Islam, I have never urinated while standing.”
[كشف الاستار: 56/1، اسناده صحيح]
Source: Sahih Ibn Khuzaymah: Commentary by Muhammad Farooq Rafee, Page: 63