Alsalamu Alaikum :) There are hadiths from the Prophet saying that Ali will be the caliph after him. "For whoever I am his Leader (after Allah of course), Ali is his Leader. O' God, love those who love him, and be hostile to those who are hostile to him." And then there are other hadiths saying "Follow the two after me, Abu Bakr and Umar." Since they are two hadiths opposing each other, clearly one isn't true. The best way then is to logically analyse the situation and events, who is more liable
Ali was always loyal to the Prophet. He was the sword of Islam. He was the second most knowledgeable person at the time after Prophet Muhammad. He was a part of Muhammad’s household. All knowledge of Muhammad was from Allah, and all knowledge from Muhammad is with Ali. He is Fatimah’s husband. He never committed a sin. He had all honesty, trustworthiness and leadership skills. He was entrusted with the money of the people at the time. “Ali is with the truth, and the truth is with Ali”
Walaykumasalaam wa rahmatullaah wa barakaatuh,
May this response find you well In shaa’ Allaah.
To address your messages, I would like to begin by mentioning an important principle from the legislation of Islaam and that is that authentic Ahadeeth cannot contradict one another. The statement of the Messenger of Allaah (ﷺ) about Abu Bakr As-Siddeeq and Umar ibn Al-Khattab (may Allaah be pleased with them) [“Follow the two after me, Abu Bakr and Umar”] has been authenticated in more than one book of Hadeeth unlike the Hadeeth regarding Ali ibn Abi Taalib (may Allaah be pleased with him).
The first sentence of the Hadeeth about Ali (may Allaah be pleased with him) can be found in the book of Imaam Tirmidhi, however the remaining portion is not to be found in any of the Kutub As-Sittah (the Six major books of Ahadeeth). Therefore, it is true that one of the Hadeeth are incorrect/weak, however this is not determined through logic, rather it is done by way of the sciences regarding the authentication of Ahadeeth.
We will now take the opportunity to understand what the people of knowledge have said about the Hadeeth you quoted a part of, In shaa’ Allaah.
The first statement in the Hadeeth, ”For whomever I am his maula, Ali is his maula…” is the only part of the Hadeeth contained in the book of Imaam Tirmidhi, which scholars such as Imaam Bukhari (may Allaah have mercy upon him), Shaykhul Islaam ibn Taymiyyaah (may Allaah have mercy upon him), and other than them have weakened, while there are other scholars who graded it hasan (good). The term ‘maula’ used in the original Arabic wording of the Hadeeth is incorrectly translated in your message, as it is does not mean ‘leader’ but ‘support’, and the scholars have said this Wilayah (unitedness with someone/support) is not specific to Ali (may Allaah be pleased with him) but is a belief which Allaah has made general between all the believers; the believers are supporters of one another.
The following wording of the Hadeeth in your message reads,
"O’ God, love those who love him, and be hostile to those who are hostile to him."
This statement along with the remainder of the Hadeeth is not to be found in any of the authentic books of Hadeeth and as noted by Imaam Ahmad (may Allaah have mercy upon him) is ‘ziyadah Kufiyyah’, a Kufi addition; meaning the people of Kufa have added it.
In his explanation, Shaykul Islaam ibn Taymiyyah (may Allaah have mercy upon him) mentioned the statement quoted above goes against the foundation of Islaam because the Qur’aan clarifies that the believers, even though they may fight and transgress one another, are believing brothers of each other. This is stated in Surah Al Hujuraat, wherein Allaah says,
"And if two parties or groups among the believers fall to fighting, then make peace between them both, but if one of them rebels against the other, then fight you (all) against the one that which rebels till it complies with the Command of Allah; then if it complies, then make reconciliation between them justly, and be equitable. Verily! Allah loves those who are equitable.
The believers are nothing else than brothers (in Islamic religion). So make reconciliation between your brothers, and fear Allah, that you may receive mercy.”
The verses above indicate that despite the two believing parties fighting Allaah addresses both with the title of believers. For this reason, to make the statement, “O Allaah, aid the one who aids him (Ali), and be hostile toward those who are hostile towards him” as quoted in the weak Hadeeth, is in opposition to what has taken place in reality and historically, because during the trouble between Mu’awiyah and Ali (may Allaah be pleased with them both), Allaah aided Mu’awiyah with opening the lands of the Kuffar to Islaam and assisting him in bringing Islaam to them.
Know to make the claim that Ali or so-and-so companion never “committed a sin” is a grave error, as no one is infallible (ma’soom) but the Messenger of Allaah (ﷺ). Haqq (the truth) does not go with Ali wherever he goes, otherwise this would mean there is unrestricted knowledge with Ali which is not true as there were Sahabah who had greater knowledge than him like Mu’adh ibn Jabal (may Allaah be pleased with him) who had immense knowledge of the Halaal and Haraam. For example, this is clear on the occasion when Ali (may Allaah be pleased with him) gave a fatwa and the other Sahabah gave a differing fatwa, as in the case of the pregnant woman who came to the Messenger of Allaah (ﷺ) upon the passing of husband to ask about the length of her ‘iddah (period of waiting) before getting married again.
Finally, Shaykhul Islaam ibn Taymiyyah (may Allaah have mercy upon him) mentioned that both Ali and Abu Bakr (may Allaah be pleased with them) have virtues, however other companions also possessed the virtues narrated about Ali but in the case of Abu Bakr there were none who shared his virtues, thereby making him the more virtuous of the two.
The scholars state Abu Bakr As Siddeeq (may Allaah be pleased with him) is the best of the Sahabah and no one denies this statement except those who go against the Qur’aan and Sunnah.
I strongly advise you to read the tafsir of Surah Al Layl to read further about the virtues of Abu Bakr As Siddeeq (may Allaah be pleased with him) and the Hijrah of the Messenger of Allaah (ﷺ), which no one else had a share in except Abu Bakr.
The book is referenced in the answer above is called, Fadl Abu Bakr As Siddeeq رضي الله عنه by Shaykhul Islaam ibn Taymiyyah. I will upload a picture of it in the following post In shaa’ Allaah.
May Allaah guide you toward understanding the truth and keep us firm upon Siraat Al Mustaqeem, Ameen.