al-Tahdhib: Sa’d b. Abdallah from Ahmad b. Muhammad from al-Husayn b. Sa’id from Hammad b. Isa from Umar b. Udhayna from Zurara who said: I was seated at Abi Ja’far’s عليه السلام place and there was no one with him except his son Ja’far, so he (Abu Ja’far) said: O Zurara, Abu Dhar رضي الله عنه and Uthman argued in the life-time of the prophet, so Uthman said: every kind wealth whether it be gold or silver which circulates [is active i.e. having in-flow and out-flow], is worked with [as a capital], and is used for business – then there is Zakat on it if a year elapses, so Abu Dhar رضي الله عنه said: as for that which is used for business, is active, and is worked with – then there is no Zakat on it, rather Zakat is on that which is buried treasure (found fortuitously) and also on stored-up (saved) wealth, so if a year elapses on it then on it is Zakat, so they argued and referred it back to the messenger of Allah صلى الله عليه وآله, so he said: the true position is what was said by Abu Dhar, so Abu Abdillah عليه السلام said to his father: you do not want anything else but that such a one [narration] comes out [and is spread among the people] so that the people stop giving their poor and needy (anything of Zakat)?! So his father said: keep to yourself [don’t interfere], I do not find any option other than it (to narrate what happened and speak the truth). (Mu'jam al Hadith al Mu'tabara)
According to the Mukhalifeen, because Imam Baqir (a) and Imam Sadiq (a) are disagreeing, then that means one of them must not be infallible.
First, there is no indication whatsoever in this hadith that Imam Sadiq (a) is questioning the hukm (the rule), rather, what he (a) is questioning the wisdom in whether this hadith should be spread among the people.
Second, Imam Sadiq (a) questioning the wisdom of spreading the hadith is done to learn from his father (a). This is not in contradiction with 'ismah (infallibility), and there is no objection if the succeeding Imam learns from the preceding Imam. It is known that the succeeding Imam does not gain full knowledge until the preceding Imam has passed away. The evidence for this is clear in Al Kafi:
Muhammad has narrated from Muhammad ibn al-Husayn from Ali ibn Asbat from al-Hakam ibn Miskin from ‘Ubayd ibn Zurarah and a group with him who has said the following. “We heard abu ‘Abdallah (a.s) say, ‘The succeeding Imam comes to know of the knowledge of the preceding Imam in the last minute of the time left from his life.’” (Al Kafi)
With that in mind, there is no objection if the preceding Imam, Imam Baqir (a), teaches the succeeding Imam, Imam Sadiq (a), or if the succeeding Imam asks questions to learn from the preceding Imam. This is not in contradiction to our beliefs in any way, nor is this in contradiction with 'ismah. Rather, even in the Quran, the angels questioned Allah's decision to create Adam (a) even though the Quran clearly testifies to the infallibility of angels from sins:
And [mention, O Muḥammad], when your Lord said to the angels, "Indeed, I will make upon the earth a successive authority." They said, "Will You place upon it one who causes corruption therein and sheds blood, while we exalt You with praise and declare Your perfection?" He [Allāh] said, "Indeed, I know that which you do not know." (2:30)
When the angels asked this question from Allah, they were not questioning Allah's wisdom, na'audhubillah, rather, they were asking to learn Allah's wisdom. We can never fathom a situation where the angels are asking to challenge Allah because Allah clearly states in the Quran:
Believers, guard yourselves and your kindred against a Fire whose fuel is human beings and stones, a Fire held in the charge of fierce and stern angels who never disobey what He has commanded them, and always do what they are commanded (66:6)
Similarly, we would never fathom that Imam Sadiq (a) would question the wisdom of his father (a) to challenge him (a) disrespectfully. Rather, as we have stated, the questioning was merely done to learn from his father (a).
Third, even if, for the sake of argument, there was a disagreement here, there would still be no problem or objection to 'ismah. Infallibility relates to doing sin or making mistakes in the ahkaam. This disagreement would only be regarding a matter of personal preference on how best to spread and teach the ahkaam and what each Imam believes to be most wise for the situation.
As we mentioned above, Imam Sadiq (a) is not questioning his father on the basis that he believes the hadith is incorrect or that he disagrees with the hukm. There is simply no evidence whatsoever in the narration that Imam Sadiq (a) thinks the ruling is incorrect. Rather, if we accept that he is disagreeing with his father, he would only be questioning whether it is wise to spread the hadith among the people.
This is no different than the disagreement between Musa (a) and Harun (a) when Musa (a) returned from Sinai.
When Moses returned to his people, ˹totally˺ furious and sorrowful, he said, “What an evil thing you committed in my absence! Did you want to hasten your Lord’s torment?” Then he threw down the Tablets and grabbed his brother by the hair, dragging him closer. Aaron pleaded, “O son of my mother! The people overpowered me and were about to kill me. So do not ˹humiliate me and˺ make my enemies rejoice, nor count me among the wrongdoing people.” (7:150)
Here, Musa (a) was angry at Harun (a) because he had a different personality and disposition. He had a personal preference as to how Harun (a) should have carried out his tabligh. As such, Allamah Tabatabai explains:
This much difference of opinion and style among the two infallible prophets can be explained by different personality types and individual orientations. We have no evidence to reject this possibility. What contravenes infallibility is disobeying divine commands, not things that boil down to personal preference and lifestyle. (Al Mizan: 93)
Likewise, the reason why Muhsini included this narration in his compilation is specifically to point out that some of the differences in the hadith of the A'imma is due to their individual dispositions and preferences:
"[Among the reasons for differences in the narrations is] differences in the opinions of the A'imma (a), whether for reasons of [what has been given in] delegation (tafwidh) [to them] or reasons other than this..." (Mu'jam al Hadith al Mu'tabara)
And then Muhsini then goes on to quote another narration as evidence that the A'imma (a) could act differently:
Through the same chain of narrators as that of the previous Hadith the following is narrated: “Abu ‘Abd Allah (a.s), has said that ’Amir al-Mu’minin, would hold a cleaner liable as well as a dyer as precautionary measures to protect the interests of the people but my father would deal with them more graciously if they were trusted ones.’” (Al Kafi)
Here, there is no disagreement between the A'imma (a) that is problematic for infallibility. In this case, Imam Baqir (a) simply chose to be more merciful to the workers, whereas Imam Ali (a) used to be more prudent. Again, neither of these effect infallibility, because neither of them are acting disobediently to Allah, nor making a mistake in the ruling.
Going back to the verse, another reason that could be given for the differences between Harun (a) and Musa (a) is simply that Musa (a) could have been unaware of the situation of Harun (a). Perhaps Musa (a) thought that Harun (a) would have been able to safely handle Bani Israil without causing division or harm to himself, but Harun (a), in his situation thought it was most prudent to stay silent and exercise dissimulation. Again, this would not cause a problem for infallibility in any way. Neither of them are incorrect, because each is acting according to his own perspective and understanding. Obviously, the prophets are not omniscient, and neither are the A'imma (a). So if Imam Baqir (a) thinks it is best to spread the hadith, then he might think so in light of his own understanding of the situation, and Imam Sadiq (a) would have also been correct according to his own understanding of the situation. In fact, when Musa (a) was told the details of what had occurred by Harun (a), he agreed with his course of action. Similarly, if Imam Sadiq (a) had all the knowledge that Imam Baqir (a) had, he likely also would have agreed with his father's decision. Like we established previously, the knowledge that is inherited with the station of the Imamate is only inherited at the moment of the previous Imam's death.
Now, regarding what Muhsini mentioned about differences due to delegation (tafwidh), this is explained by narrations where the A'imma (a) say that they have been given freedom in the methods they use in how to spread the religion:
Ahmad ibn Idris and Muhammad ibn Yahya have narrated from al-Hassan ibn Ali al-Kufi from ‘Ubays ibn Hisham from ‘Abdallah ibn Sulayman who has said the following “I asked abu ‘Abdallah (a.s) about the Imam. Has Allah made him the in charge of the and in full control (fawwada) (over the affairs of the people) as Sulayman ibn Dawud was?” The Imam (a.s) said, “Yes, it is like that. It is because a man asked him a question and he gave the answer. Another person asked the same question and he gave him a different answer (although the question was the same). A third person asked him the same question and he gave an answer that was different from both the previous answers. Then he said, “This is Our gift to you so give them away free or keep them as you like.” (38:39). This is charity from us enjoy it with thanks or ( give to others) without being questioned. This is according to Imam Ali’s recitation.” ... (Al Kafi)
For example, A'imma (a) can choose to answer people according to their personal circumstances, or choose to answer with more general rules:
Ali ibn Ibrahim has narrated from his father from ibn abu Najran from ‘Asim ibn Humayd from Mansur ibn Hazim who has said the following. “I said to (Imam) abu ‘Abdallah (a.s), ‘It is confuses me that when I ask you a question and you give an answer and then other person comes and you give a different answer for the same question.’” The Imam replied, “We answer people in a larger and reduced forms.” (Al Kafi)
This is all within the purview of the A'imma (a). They have full freedom in answering, or refusing to answer, or controlling how certain teachings are presented or taught. Of course, they do not have power over the Shari'a itself. (See "Completion of Religion & Teachings of the Imams" for a further discussion of this topic). Hence, if one Imam (a) chooses not to publicly spread one ruling and another believes it is most wise to spread it, there is no contradiction with infallibility.