بسم الله الرحمن الرحيم
Assalamu Alaykum wa Rahmat Allahu wa Barakatu, there are speculative Ahadith (thaniyya athuboot) that we use as proof when we interact with people to spread the idea of Islam when we herald the tidings of Allah's Prophet (saw) such as the Hadith:
«تَكُونُ النُّبُوَّةُ فِيكُمْ مَا شَاءَ اللهُ أَنْ تَكُونَ... ثُمَّ تَكُونُ خِلَافَةً عَلَى مِنْهَاجِ نُبُوَّةٍ»
"Prophethood will last among you for as long as Allah wills... Then there will be a Rightly Guided Khilafah upon the ways of the Prophethood."
The question: This Hadith is speculative and speaks about the political conditions that will pass on the Ummah, and one of the meanings of the Hadith is that the Prophet divided the conditions into five conditions (the Prophethood - Rightly-Guided Khilafah - biting rule - oppressive rule - Rightly-Guided Khilafah), so when we see that four fifths of the Hadith have fallen on the Ummah, does this not promote this Hadith to the rank of Mutawatir, on the grounds that part of it has taken place?
The Hadith is sufficient which holds the meaning of a call to action, whether it is Mutawatir or speculative (thanniya),as long as it is a Sahih Hadith, that to strongly encourage action according to what it contains of Fard.
For example, the Hadith:
«لَتُفْتَحَنَّ الْقُسْطَنْطِينِيَّةُ، فَلَنِعْمَ الْأَمِيرُ أَمِيرُهَا، وَلَنِعْمَ الْجَيْشُ ذَلِكَ الْجَيْشُ»
"Constantinople will be conquered, what an excellent leader is its leader and what an excellent army is its army" (Ahmad)
Even though the Hadith conveys news it also has the meaning of a call to action, and therefore every Muslim ruler was keen that the Hadith be realized during his rule, so they send equipped armies to Constantinople, until Allah bestowed Muhammad al-Fatih with this conquest, and like this Hadith is the Hadith about fighting the Jewish state and its eradication... and likewise the Hadith about the coming Khilafah on the method of the Prophethood, so it does not matter if the Hadith is Mutawatir or not Mutawatir as long as the Hadith is Sahih, and we continue on the path so that it will be realized on our account Insha'allah, and take glad tidings, and are assured of its realization sooner or later, and do not tire ourselves dealing with the details to know if it is Mutawatir or Ahad.
With all this, the realization of part of the Hadith reassures us that the rest of the Hadith will be realized, like the conquest of Rome after the conquest of Constantinople, as the conquest of both cities is mentioned in another of the Prophet's Hadiths, but as I mentioned earlier, there is no need to delve into the Tawatir of a Hadith that means a call to action because the Hadith that is Sahih but speculative (thanni) is sufficient for action, conviction and assurance, and to take tidings of its realization, and the Muslim is keen to win this favor.
Regarding your statement: "as long as the part of the Hadith has been realized, do we consider it Mutawatir?" The answer is that the Mutawatir Hadith has certain requirements for the chain of narration that is adopted by the Science of Hadith to determine if it is Mutawatir, meaning that according to this science, the Hadith being Mutawatir does not depend on the realization of the Hadith or not, because the Mutawatir Hadith is judged according to its chain of narration, and nevertheless the realization of parts of the Hadith gives the heart more reassurance in the correctness of the Hadith, and it is an incentive to vigorously act to realize the remaining part, and Allah the Almighty is the Guardian of success.
18 Rabi' I 1434