Accountability for the things which we do not know
It is not uncommon when we look at the expansiveness of Fiqh and other Islamic sciences to wonder what exactly and to what extent are we accountable for seeking knowledge and acting on it. Surely it can’t be the every Muslim must know all details of all rulings or else he/she will be sinful. Regarding this fundamental question Mufti Abdurrahman ibn Yusuf has the following to say.
It is necessary for every Muslim to acquire the knowledge of the essentials of his faith. For instance, it is necessary for a person to know the rulings for his everyday issues like purity, salat, etc. Thereafter, if a person earns sufficient wealth that makes him eligible to pay zakat or make the pilgrimage, then he is also required to learn the laws of zakat and haj. He needs to also learn the spiritual aspects of his din like how to make his actions exclusively for the sake of Allah. Besides this, it is also necessary for him to learn social conduct, i.e. how to interact properly with the creation of Allah.
In other words, it is legally binding (fard) on all Muslims to possess sufficient knowledge to discharge their everyday duties, which means a thorough knowledge of the basics of prayer, wudhu, ghusl, what one can eat and what one cannot, etc. (‘Allama Ibn ‘Abidin’s supercommentary on al-Durr al-Mukhtar 1:29)
The Prophet sallallahu alayhi wasallam said, “Seeking knowledge is obligatory upon every believing person” (Sunan Ibn Maja, Bayhaqi).
This has been explained as the obligation of acquiring the knowledge of the essentials of ones faith. Beyond the basic essentials, it would only be necessary to learn the details of other related issues if they arise. However, it is a communal obligation to have access to experts in jurisprudence (a mufti or faqih) who can answer these questions when they arise.
If a person has not acquired the basics essentials of his faith and is making mistakes in that regard, he is surely considered to be blameworthy. If a person, on the hand, tried to the best of his ability to learn the basic essentials of his din, then missed out on something, he may be excused by Allah. In any case, once a person discovers a mistake in what they were doing he may be able to correct it (in some cases) by redoing the action [qada] otherwise only repentance would be necessary.
Even after learning the essentials of ones din (for instance at a din intensive or by a local teacher) a person must continue to refresh his knowledge by practicing upon it and studying further. Otherwise it is sometimes very easy to lose this knowledge.
And Allah knows best.