In The Name of Allaah, The Most Merciful, The Bestower of Mercy.
Indeed, 1444 years ago the final Messenger [peace and blessings of Allaah be upon him] taught us everything about perfect beliefs, manners, etiquettes, mutual dealings, personal hygiene and many other matters. Allaah [The Exalted] said:
[لَقَد كانَ لَكُم في رَسولِ اللَّهِ أُسوَةٌ حَسَنَةٌ لِمَن كانَ يَرجُو اللَّهَ وَاليَومَ الآخِرَ وَذَكَرَ اللَّهَ كَثيرًا – Indeed in the Messenger of Allah (Muhammad ) you have a good example to follow for him who hopes in (the Meeting with) Allah and the Last Day and remembers Allah much]. [Surah Al-Ahzaab. Aayah 21]
Firstly, read a fatwa in which is mentioned some of the authentic narrations on this subject matter: https://www.fatwaislam.com/fis/index.cfm?scn=fd&ID=88
Secondly, when would it be better to sit or stand depending on circumstances? Imaam Abdul Azeez Bin Baaz [may Allaah have mercy upon him] said: “There is nothing wrong with urinating, whilst standing, especially when there is a need for it. If the place (of urination) is concealed and no one can see the private parts of the person who is urinating and nothing from splashback touches him; but it is better to urinate while sitting because this is mostly what the Prophet [peace and blessings of Allaah be upon him] did. It is what enables one – the most – to conceal the private parts and distance oneself from the splashback. (1)
Al-Allaamah Saalih Al-Fawzaan [may Allaah preserve him] stated: It is dislike (in the Sharee’ah) that a person urinates whilst standing; except out of a need, such as when a person has an illness that makes him unbale to sit down, then there is no harm in standing whilst urinating; or the place is dirty and unclean, and if he sat, he would be defiled it, because it is a place of impurities, or because there is sludge and mud in it, so a person becomes dirty if he sits; then there is no objection to him urinating while standing due to an excuse. As for standing without an excuse, it is disliked (in the Sharee’ah) for a person to urinate while standing, because that may be a reason for him (i.e. his other body parts and clothes) to come into contact with impurity and the splashback. And Allaah [The Exalted] knows best. (2)
An Example of Those Who Strayed – In The Subject Matter of Purification – Towards The Path of Those Ahlul Kitaab Who Strayed From The Path of Their Prophets: https://salaficentre.com/2021/09/30/an-example-of-those-who-strayed-in-the-subject-matter-of-purification-towards-the-path-of-those-ahlul-kitaab-who-strayed-from-the-path-of-their-prophets/
The reason behind this article is that after coming across an article in the guardian newspaper [https://www.theguardian.com/society/2023/feb/20/the-splashback-scandal-should-all-men-sit-down-to-urinate], it reminded us of this subject matter that is found in the authentic Sunnah of the final Messenger [peace and blessings of Allaah be upon him] as well as some statements of the scholars. This affair was already dealt with 14444 years ago.
Read article by Shaikh Abu Khadeejah [may Allaah preserve him] “Manners of visiting the toilet and keeping one’s nakedness from the sights of the people”: https://abukhadeejah.com/manners-of-visiting-the-toilet-and-keeping-ones-nakedness-from-the-sights/
Comprehensive Guidance of The Messenger – By Imaam Ibnul Qayyim [rahimahullaah]
Imaam Ibnul Qayyim [may Allaah have mercy upon him] said: Muhammad’s [peace and blessings of Allaah be upon him] Ummah is not in need of anyone after him; rather the only need they have is someone to convey what he came with. Muhammad’s message is comprehensive, universal and preserved. This universality, comprehensiveness and preservation is not limited to [any time and place], rather it is comprehensive for those to whom Muhammad was sent [i.e. the whole world] and likewise with regards to everything that is needed in the fundamental and subsidiary issues of the religion.
Muhammad’s message is sufficient, all embracing and universal- nothing else is needed besides it. It has not isolated any affair of truth needed by his Ummah in their sciences and deeds. The Messenger of Allaah did not leave this world until he acquainted his Ummah with everything. He even taught them the etiquettes of using the toilet; the etiquettes of sexual relations; the etiquettes of sleep and after waking up; the etiquettes of eating, drinking and travel.
He acquainted them with the etiquettes of speech and silence; the etiquettes of keeping company with the people and seclusion. He acquainted them with the affairs of illness, good health, poverty and wealth. He acquainted them with all the affairs of life and death. He described Allaah’s throne, the angels, the jinn, the hell fire and the day of judgement in such a manner as if one has seen them with the naked eye. He [sallal-laahu-alayhi-wasallam] informed them about their Lord and His Perfect Names and Attributes, and that Allaah alone is their true object of worship.
He acquainted them with the Prophets of old and their nations – the events that took place between them and their nations – in such a manner as if one was present at that time. He acquainted them with all the means to good and the paths of evil- in general and in detail- which no other prophet informed his nation. He acquainted them with death and what will take place in the grave – either bliss or punishment. He acquainted them with the evidences and proofs of Tawheed [i.e. the oneness of Allaah in His Lordship, Names and Attributes, and that Allaah alone has the right to be worshipped].
He acquainted them with Prophet hood and the affairs of the Afterlife, and he refuted all the sects of disbelief and misguidance. He acquainted them with war strategies- how to confront the enemy, the way to achieve victory and conquests. If only they knew and understood these affairs in the correct manner [i.e. the manner it should be understood], they would not be overcome by their enemy. He acquainted them with the plots of Iblees and the ways through which he approaches them, and the ways to repel those plots and plans. He acquainted them with the soul- its characteristics and faults- in such a manner that they are not in need of anyone else to tell them about it. He taught them how to live their daily lives and had they acknowledged and acted upon this; their worldly affairs would be firmly established. He brought them all the means of success in this life and the next, and they do not need anyone besides him. So how can it be said that the path of Muhammad is in need of something else outside of it. The reason for such a claim is due to the weak and little understanding of a person. Allaah [The Most High] said: [أَوَلَمْ يَكْفِهِمْ أَنَّا أَنزَلْنَا عَلَيْكَ الْكِتَابَ يُتْلَىٰ عَلَيْهِمْ ۚ إِنَّ فِي ذَٰلِكَ لَرَحْمَةً وَذِكْرَىٰ لِقَوْمٍ يُؤْمِنُونَ – Is it not sufficient for them that We have sent down to you the Book (the Qur’an) which is recited to them? Verily, herein is mercy and a reminder (or an admonition) for a people who believe. [29:51]
Allaah [The Most High] said: [وَنَزَّلْنَا عَلَيْكَ الْكِتَابَ تِبْيَانًا لِّكُلِّ شَيْءٍ وَهُدًى وَرَحْمَةً وَبُشْرَىٰ لِلْمُسْلِمِينَ – And We have sent down to you the Book (the Qur’an) as an exposition of everything, a guidance, a mercy, and glad tidings for those who have submitted themselves (to Allah as Muslims). [16:89]
Allaah [The Most High] said: [يَا أَيُّهَا النَّاسُ قَدْ جَاءَتْكُم مَّوْعِظَةٌ مِّن رَّبِّكُمْ وَشِفَاءٌ لِّمَا فِي الصُّدُورِ وَهُدًى وَرَحْمَةٌ لِّلْمُؤْمِنِينَ – O mankind! There has come to you a good advice from your Lord [i.e. the Qur’an, ordering all that is good and forbidding all that is evil], and a healing for that [disease of ignorance, doubt, hypocrisy and differences, etc.] in your breasts, – a guidance and a mercy [explaining lawful and unlawful things, etc.] for the believers]. [10:57] (3)
Benefit from this article by Shaikh Abu Khadeejah “Issues which arise after the time of Revelation for which there is no specific text: Al-Masālih Al-Mursalah and how Islam is applicable in every age” https://abukhadeejah.com/issues-which-arise-after-the-time-of-revelation-for-which-there-is-no-specific-text-al-masalih-al-mursalah-and-how-islam-is-applicable-in-every-age/
[Ref 1: Majmoo Fataawaa 6/445]
[Ref 2: Majmoo Fataawaa Fadheelah Ash-Shaikh Saalih Al-Fawzaan 2/719
[Ref 3: An Excerpt from I’laam Al-Muwaqqi’een 4/375-377- slightly paraphrased]