The term imamate or imamah (Arabic: إمامة, imāmah) means "leadership" and refers to the office of an imam or a state ruled by an imam.
According to Twelver Shi'i narrations, the knowledge of the Imams is received through divine sources. It is available throughout their lives but culminates to a new level after the departure of the previous Imam (or, in the case of Imam Ali, the Prophet). They have access to anything they need or want to know. This knowledge is available to them at any time; however, at certain times, certain specific information is presented to them (such as the deeds of their followers).
It is considered to be a step lower than the type of wahy given to the messengers. For instance, some narrations say that the Imams can hear the angel Jibra'il but not see him. Similarly, the Imams provide guidance, but not a revealed scripture like the Qur'an which is a Book in the word of Allah.
The mechanics of how this knowledge is acquired in mentioned in some narrations, although these narrations tend to be somewhat obscure and may or may not be accurate. In any case, it is said that the Imams have access to something resembling a column of light or a lamp between themselves and Allah through which they can attain knowledge of anything or to see any place. In other places, it is simply said that the Imams were created with certain types of knowledge, such as knowledge of the explanation of the Qur'an and other fundamentals regarding the nature of this world and the worlds before and afterwards. There are also some texts the Imams possessed such as Mushaf Fatima and Kitab Ali, although it is not said that they required these texts to know what was in them.
Insofar as knowledge is potentially infinite, all of these things could be accepted altogether without contradiction .
In any case, this is a large and complex subject, so to learn more about it, one could read hadith collections such as Basa'ir al-Darajat and al-Kafi.
All the Prophets faced injustice and many of them were killed like Prophet Yahya, but never used divine power or miracles. Allah Wants life to go according to the same system that He created. Allah (SWT) does not use His divine Power against those who disobey Him because He leaves people to do whatever they decide and postpone the final result to the Day of Judgement.
Using divine power will then force people to believe which is against the principle of testing people to make them choose between right and wrong.
Thank you for your question. The idea of knowledge which comes from Allah through metaphysical means, rather than through normal means of acquisition has been derived by Muslim thinkers reflecting on verse 18:65 in which Khidr is described as having this trait.
If the definition of ilm al-ladunni is as mentioned above then revelation is the highest form of this type of knowledge, followed by hadith qudsi and then other types of mystical experience. We have plentiful reports about such types of mystical experiences occurring in the life of the Prophet (saw) and the Imams (as). If it seems incoherent that the knowledge of the Imams (as) is only acquired from their study of the Prophetic sunna, then a reasonable explanation would be some level of ilm ladunni. Some commentators have explained ilm al-ladunni as prophethood, and Allah knows best.
May you always be successful
Allah ordered in Quran : Take and follow whatsoever the Messenger of Allah tells you, and abstain from whatsoever he forbids you. (Sura 59, verse 7).
This Quranic order is very clear and obligatory on every believer. Lot of very important matters in Islam were not mentioned in Quran but ordered by the Prophet ( SAWA) hence became obligatory on all Muslims like the number of Rak'ats in every Salaah (Prayer). All Muslims perform Morning Prayers in two Rak'ats, Dhuhr in four Rak'ats, Asr in four Rak'ats, Maghrib in three Rak'ats and Isha in four Rak'ats just because the Prophet told them and Allah's order in Quran (Sura 59, verse 7).
Allah says in Quran as well : He who obeys the Prophet has indeed obeyed Allah. (Sura 4, verse 80).
The Prophet Muhammad (SAWA) has clearly and repeatedly mentioned that his successors will be 12 Imams. This has been mentioned in most authentic Hadeeths narrated in both Shia and Sunni main references like:
1. Saheeh Al-Bukhari , Hadeeth number 6682.
2. Al-Tareekh Al-Kabeer by Al-Bukhari, Volume 8, page 410.
3. Saheeh Muslim , Hadeeth number 3393 and 3394 and 3395 and 3396 and 3397 and 3398.
4. Musnad Ahmad ibn Hanbal in 36 Hadeeths ; 3593 and 3665 and 9875 and 19884 and 19887 and 19892 and 19901 and 19914 and 19920 and 19920 and 19925 etc.
5. Tirmithi (Tirmizi) Hadeeth number 2149.
6. Sunan Abi Dawood , Hadeeth 3731 and 3732.
7. Mustard Al Al-Saheehain by Al-Haakim Al-Nisabouri, Hadeeths 6586 and 6589 and 8529.
8. Al-Albani Nasser Al-Deen, Kuruba Takhreej Al-Hadeeth, Hadeeth 376 and 1075 and 3598 and 3599.
9. Ibn Hajar Al-Asqalani in Ta'jeel Al-Manfa'ah, page 538, and in Al-Mataalib Al-'Aaliyah , 2140 and 4608.
10. Al-Bayhaqi in Dala'il Al-Nubowwah, Hadeeth 2589 and 2888 and 2890 and 2895
And many other Sunni books.
The fact of the Twelve Imams after the Prophet of Islam is an order from Allah (SWT). No one has right to say or suggest on any matter which has been decreed by Allah (SWT). Allah Knows every thing including all the future, so, there is no point in putting such questions from us. Allah Knows everything and He is The Absolute Wise, All Knowung, Most Merciful.
As the Abbasid government rulers' pressure on Imam Hasan Al-Askari (AS) and his family was tremendous, the disclosure of Imamate of Imam Mahdi (AS) was among the near circle of the most trusted persons. Imam Hasan Al-Askari (AS) told very few most trusted believers and allowed them to see his successor Imam Al-Mahdi (AS). These are names of some of those who saw Imam Al-Mahdi (AS):
1. Othman ibn Sa'eed Al-Amri who became later the first Safeer of the Imam Al-Mahdi (AS).
2. Muhammad ibn Othman ibn Sa'eed Al-Amri, who became later the second Safeer of the Imam.
3. Al-Husain ibn Rooh.
4. Ali ibn Muhammad Al-Samari.
5. Lady Hakimah daughter of Imam Al-Jawad (AS).
6. Ibraheem ibn Mahziyar Al-Ahwaazi.
7. Ahmad ibn Eshaq ibn Sa'd Al-Ash'ari.
8. Ahmad ibn Muhammad ibn Al-Mutahhar.
9. Ismael ibn Ali Al- Nawbakhti.
10. Ali ibn Ibraheem ibn Mahziyaar Al-Ahwaazi.
11.Kaamil ibn Ibrahim Al-Madani.
13. Muhammad ibn Ismael ibn Musa Al-Kadhim.
14. Al-Hasan ibn Wajnaa' Al-Naseebi.
15.Ibrahim ibn Idrees.
16. Ibrahim ibn A'bdah Al-kNisabori.
17.Ibrahim ibn Muhammad Al-Tabreezi.
18. Sa'ad ibn Abdullah ibn Abi Khalaf Al-Ash'ari.
19. Ali ibn Muhammad Al-Shimshaati.
20- Muhammad ibn Al-Qasim Al-Aqeeli.
There are hundreds of well known pious believers who saw Imam Al-Mahdi (AS). Whole books were been compiled on this subject by big scholars.
There is a full field of knowledge called E'lm Al-Rijaal which deals with every narrator and searching and assessing his authenticity. Deviat persons are known by our scholars of E'lm Al-Rijaal and their narrations are never accepted.
Famous Shia books on E'lm Al-Rijaal are like Kitab Al-Rijaal by Al-Najaashi (450 Hijri),
Rijaal Al-Kashshi (350 Hijri) ,
and Al-Fahrist by Al-Shaikh Al-Tousi (460 Hijri) ,
Ma'aalim Al-Ulama' by Ibn Sharashoob 588 hijri.
Khulasat Al Awwal by Al-Allama Al-Hilli 726 hujri.
Tanqeeh Al-Maqaal by Al-Mamaqani 1351 hujri.
and Mu'jam Rijaal Al-Hadeeth by Al-Khoei 1413 hijri.
We only accept narrations from authentic narrators who were always in the right path.
In our Shi'i belief, there is only one female who has 'ismah (infallibility), and that is Seyyidah Fatimah al-Zahraa (a.s.).
There are different dimensions to your question and answer, and I have covered it in a presentation which in shaa Allah could assist in answering your question:
It is highly recommended to sacrifice on Eid Al-Adha, but it is not obligatory except on pilgrims in Hajj. The narration you mentioned means the importance of the sacrifice and the great reward of it but does not mean that it is obligatory.
The Twelve Infallible Imams from Ahlul Bayt (AS) did inherit the knowledge of the Prophet Muhammad (SAWA). That is why, their status is from his status as Allah says in Quran ذُرِّيّةً بَعْضُها مِن بَعض A Progeny (of the Prophet) which part from him. Their status is higher than everyone except the Prophet Muhammad (SAWA) who is The Highest over all creatures.
I would like to direct you to something I wrote on my website regarding your important question. Although it is long, but it will hopefully explain this misconception in detail.
With prayers for your success.
The status of all the Infallible Imams (AS) is derived from the status of the Prophet Muhammad (SAWA) which is the highest among all the Prophets before him.
Allah says in Quran: A Progeny every one from them is from the others ذُرّيّةً بَعضُها مِن بَعض
This means that the Prophet's status and his Progeny's status are one from the another.