The ruling on whether it is from the Sunnah to drink while sitting or while standing
23-1-2016 | IslamWeb
Question:
What is Sunnah? Does Sunnah mean the things that Prophet Muhammad, sallallaahu 'alayhi wa sallam, did? People say that drinking while sitting is Sunnah and not in the standing position. However, in one of your fatwas (50836), you quoted a hadith from An-Nasaa’i that says that the Prophet used to drink both standing and sitting (narrated by Aa'ishah, may Allaah be pleased with her). So are both Sunnah?
Answer:
All perfect praise be to Allaah, The Lord of the Worlds. I testify that there is none worthy of worship except Allaah and that Muhammad 
is His slave and Messenger.
According to Hadeeth scholars, the term 'Sunnah' is not confined to the actions of the Prophet ; rather, it is defined as: All that is attributed to the Prophet of his statements; actions; (tacit or clear) approvals (or disapprovals); and reports that describe his physical features, character traits and attributes.
It seems that the 'Sunnah' that you are asking about is that which means 'recommended'. In Fiqh (Islamic law) terminology, Sunnah denotes actions as being recommended as opposed to being obligatory. There are many ways of identifying the recommended acts (i.e. the acts of Sunnah). Dr. ʻIyaadh As-Salmi wrote:
"A recommended act is identified by many ways including the following:
1) The command is accompanied with indications suggesting that non-compliance with the command is permissible. For instance, Allaah, The Exalted, says (what means): {...And those who seek a contract (for eventual emancipation) from among whom your right hands possess - then make a contract with them if you know there is within them goodness...} [Quran 24:33] The command in this case conveys recommendation or permission merely and not an obligation because the Prophet did not emphasize the obligation that the Companions must accept making such a contract with their slaves. Rather, he approved retaining their slaves though he knew that 'there is within them goodness.'
2) The encouragement to do such an act by underlining its rewards without commanding that it should be done. For example, the Prophet said, 'He who utters ten times, 'La ilaaha illa Allaah, wahdahu la shareeka Lah, Lahu Al-Mulku wa Lahu Al-Hamdu, wa Huwa ʻala kulli shay'in Qadeer.' (No deity is worthy of worship save Allaah; He is One and He has no partner with Him. His is the sovereignty and His is the praise, and He is over everything Omnipotent.) (The one who says that) will have a reward equal to that for freeing four slaves from the progeny of (Prophet) Ismaʻeel.' [Al-Bukhari and Muslim]
3) Highlighting that Allaah, The Exalted, loves such an act. The Prophet said, 'There are two statements that are light on the tongue, heavy in the scales, and dear to the Merciful: 'Subhaan Allaah wa bihamdih, Subhaan Allaah Al-ʻAtheem.' (Glory be to Allaah and His is all due praise, (and) Glory be to Allaah, the Most Great.)' [Al-Bukhari and Muslim]
4) Praising the doer of such an act; Allaah, The Exalted, says (what means): {And the servants of the Most Merciful are those who walk upon the earth easily, and when the ignorant address them [harshly], they say [words of] peace.} [Quran 25:63]
5) The fact that 'The Prophet carries out such an act without commanding Muslims to do it, such as the iʻtikaaf (observing retreat in the mosque for the sole purpose of worship and devotion to Allaah).'" [Usool Al-Fiqh Allathi Laa Yasaʻu Al-Faqeeh Jahluh]
Knowing that, you come to realize that the fact that the Prophet carried out a given deed is one of the ways of identifying recommended acts.
As for drinking while sitting down, it is an act of Sunnah as it has been authentically reported that the Prophet forbade drinking while standing in more than one hadeeth. As for the reports that he drank while standing on certain occasions, he did so to demonstrate that there is a concession in this matter and that drinking while standing is not prohibited and that drinking while sitting is a Sunnah (recommended) and that it is permissible not to do it. An-Nawawi 
wrote:
"There is no contradiction in these ahaadeeth, praise be to Allaah, and none of them are weak; rather, they are all authentic. The correct view is that the prohibition mentioned in them is to be understood as meaning that it is merely non-prohibitively disliked (makrooh tanzeehan). The fact that the Prophet drank whilst standing indicates that it is permissible to do so. This is all that needs to be said on the matter. If it is asked, 'How come it is deemed disliked to drink whilst standing when the Prophet did that?' The answer is that if what he did was to show that it is permissible, then his action is not disliked; rather, he was obliged to show and explain that, so how can it be disliked? It is proven that the Prophet performed ablution washing each body part only once and that he circumambulated the Kaʻbah (i.e. did tawaaf) riding a camel – even though there is a scholarly consensus that it is better to perform ablution washing each body part three times and that it is better to do tawaaf while walking. There are many similar examples. The Prophet used to demonstrated that something is permissible one time or many times, but he persisted in following the better option. So, when he did ablution, he mostly washed each part three times, and he mostly did tawaaf walking, and he mostly drank whilst sitting. This is clear and is not confusing to anyone who has the slightest claim to knowledge."
Allaah knows best.