I was looking in the Hadith literature to find in what connotation did the Prophet (pbuh) and companions used the term Sunnah. I found that the companions of the Prophet (pbuh) and Muhadittin scholars have used Sunnah to include all the minor actions, details of the Prophet (pbuh).This means that term Sunnah as found in the Hadith literature is very much in line with the classical definition of the Sunnah rather than your definition of Sunnah.
Please look at the hadiths below:
Yahya related to me from Malik from Sadaqa ibn Yasar that al-Mughira ibn Hakim saw Abdullah ibn Umar sit back from the two sajdas of the prayer onto the top of his feet. When he had finished, al-Mughira mentioned it to him, and Abdullah ibn Umar explained, “It is not a Sunnah of the prayer. I do it because I am ill.” (Book 3, Number 3.13.53, Malik Muatta)
Yahya related to me from Malik from Abd ar-Rahman ibn al-Qasim that Abdullah ibn Umar told him that he used to see Abdullah ibn Umar cross his legs in the sitting position of the prayer. He said, “So I did the same, and I was young at the time. Abdullah ibn Umar forbade me and said, ‘The Sunnah of the prayer is that you keep your right foot vertical and lay your left foot down.’ I said to him, ‘But you do the same (as I did).’ He said, ‘My feet do not support me” (Book 3, Number 3.13.54, Malik Muatta)
In the above hadith, even placing of the feet vertical during Tashahud position is also considered as a Sunnah. Such minor details are fixed in prayer.
Narrated Al-Barraa: The Prophet said (on the day of Idal-Adha), “The first thing we will do on this day of ours, is to offer the (‘Id) prayer and then return to slaughter the sacrifice. Whoever does so, he acted according to our Sunnah (tradition), and whoever slaughtered (the sacrifice) before the prayer, what he offered was just meat he presented to his family, and that will not be considered as Nusak (sacrifice).” (On hearing that) Abu Burda bin Niyar got up, for he had slaughtered the sacrifice before the prayer, and said, “I have got a six month old ram.” The Prophet said, ‘Slaughter it (as a sacrifice) but it will not be sufficient for any-one else (as a sacrifice after you). Al-Bara’ added: The Prophet said, “Whoever slaughtered (the sacrifice) after the prayer, he slaughtered it at the right time and followed the tradition of the Muslims. (Volume 7, Book 68, Number 453, Bukhari)
Narrated Sa’id bin ‘Ubada Al-Ansari: that he consulted the Prophet about a vow that had been made by his mother who died without fulfilling it. The Prophet gave his verdict that he should fulfill it on her behalf. The verdict became Sunnah (i.e. the Prophet’s tradition). (Volume 8, Book 78, Number 689, Bukhari)
In the above hadith, even a saying of the Prophet (pbuh) is regarded as Sunnah by the companions of the Prophet (pbuh).
Narrated Anas bin Malik: A group of three men came to the houses of the wives of the Prophet asking how the Prophet worshipped (Allah), and when they were informed about that, they considered their worship insufficient and said, “Where are we from the Prophet as his past and future sins have been forgiven.” Then one of them said, “I will offer the prayer throughout the night forever.” The other said, “I will fast throughout the year and will not break my fast.” The third said, “I will keep away from the women and will not marry forever.” Allah’s Apostle came to them and said, “Are you the same people who said so-and-so? By Allah, I am more submissive to Allah and more afraid of Him than you; yet I fast and break my fast, I do sleep and I also marry women. So he who does not follow my Sunnah is not from me (not one of my followers).” (Volume 7, Book 62, Number 1, Bukhari)
In the above hadith, marriage is considered as a Sunnah of the Prophet (pbuh).But I read in one of your response that marriage for a person is not compulsory and he can remain unmarried throughout his life if he wishes to do so. Doesn’t the verdict contradict the above hadith.
One of the most important points in the proper understanding of the language of the Qur’an and that of the sayings ascribed to the Prophet (pbuh), in particular, and any other literature, in general, is that when it uses a particular word as a ‘term’ or in a meaning, which is more qualified than the literal meaning of that word, it does not automatically imply that it would never use that particular word in its commonly used literal meaning.
Keeping the foregoing clarification in perspective, if we take a look at the literal meaning of the word ‘Sunnah’, it means the generally “treaded path”. Over time, it came to be used for a common practice of a person a group or a culture. Parallel to this general literal connotation, ‘Sunnah’ is also a religious term.
In its literal meaning, the word ‘Sunnah’ can be used for any regular – and even not so regular – practices of the Prophet (pbuh) and it can also be used for any actions which are in accordance with the teachings or recommendations of the Prophet (pbuh). Similarly, the phrase ‘Sunnah among the Muslims’ can be used for any practice adopted by the Muslims.In Quran the word sunnah is used for Allah’s practices many times.
Thus, from a literal perspective, the Prophet’s style of placing his feet during tashahhud may be considered as a ‘Sunnah’ of the Prophet (pbuh). Nevertheless, if the Prophet (pbuh) did not prescribe a specific style of placing one’s feet during tashahhud, for all the Muslims, then the style of the Prophet (pbuh) cannot be considered as a matter of the Shari`ah. Similarly, a practice recommended by the Prophet (pbuh) may be considered as his ‘Sunnah’, using the word in its common literal sense. However, this recommendation of the Prophet (pbuh) may or may not be a considered as a ‘Sunnah’ – in the sense of the term of the Shari`ah.
In the light of the foregoing explanation, consider the following narrative:
روي أنه قال النبي صلى الله عليه وسلم صلوا قبل صلاة المغرب قال في الثالثة لمن شاء كراهية أن يتخذها الناس سنة (بخاري، رقم الحديث 1128)
It is narrated that the Prophet (pbuh) said: ‘Offer [supererogatory] prayers before Maghrib.’ The Prophet repeated this sentence three times. When he repeated the words the third time, he added: ‘Whoever wants to do so’, fearing that people might construe it as ‘Sunnah’.
It is obvious that if the word ‘Sunnah’, as a term of the Shari`ah, was used generally for all the practices, likes, dislikes, preferences, recommendations and sayings of the Prophet (pbuh), then offering supererogatory Rak`ahs before the Maghrib prayers could safely be termed as his ‘Sunnah’. Yet we see that it is not.
I hope our explanation would clarify the usage of words in varying connotations in a piece of literature and, thereby, remove the confusion that this varying usage can, sometimes, cause.
As for your last comment, in the last cited narrative, the word ‘Sunnah’ is not used for ‘marriage’ but is, in fact, used for the general balanced attitude of the Prophet (pbuh) towards life.
Hope this helps.