How do fard and wajib differ?

What is the difference between Fard and Wajib?

In fact, there is only one classification of ibadats and that is fard.

The source of Islam is the Koran. If something is ordered in the Koran, it is a fard, it is an ibadat. Something that is prescribed in the Qur'an is compulsory and needs to be done.

What happens if something is not ordered in the Koran, but Rasul orders it?

مَّنْ يُطِعِ الرَّسُولَ فَقَدْ أَطَاعَ اللّهَ وَمَن تَوَلَّى فَمَا أَرْسَلْنَاكَ عَلَيْهِمْ حَفِيظًا
Whoever obeys the Messenger has obeyed Allah. but those who turn away - We did not send you to watch over them.
Nisa 80 (4/80)

If Rasul commands something (without Allah expressly commanding it in the Qur'an), it is fard again. A duty to do.

Then what happens if something in the Qur'an is not flawed, not commanded by Rasul, but Rasul does it regularly?

لَقَدْ كَانَ لَكُمْ فِي رَسُولِ اللَّهِ أُسْوَةٌ حَسَنَةٌ لِّمَن كَانَ يَرْجُو اللَّهَ وَالْيَوْمَ الْآخِرَ وَذَكَرَ اللَّهَ كَثِيرًا
In the Messenger of Allah surely there was an excellent pattern for everyone who hopes in Allah and the last day and who often remembers Allah.
Azhab 21 (33/21)
The lawful translation of the bold part is "a good example for those who want to attain Allah and the day of Kiyamat".

Doing what Rasul does (but does not specifically command) must be taken as a good example if we are to achieve Allah and the day of Kiyamat.

From the entire Quran we conclude that it is very important for a Moomin to want to reach Allah. Abbreviation for this is to live as Rasul lived. At this point it is important to understand what "life like Rasul" means. It doesn't mean doing the exact things he did in his day. One should understand one's reasons in one's actions and adapt them perfectly to one's life. For example, Rasul Muhammad (pbuh) brushed his teeth with a piece of wooden stick. That doesn't mean that we have to prefer wooden sticks to brushing our teeth. There was no toothbrush in his day. Taking him as an example, you should understand that the reason he used this wooden stick was to keep his mouth clean and to halal adapt this reason to his own life with the best technology he can find according to his terms can (economy), social rules, etc.).

So there is only one category of ibadats. that's fard. Wajib means "duty" in Arabic. But it is not something to categorize the ibadats in Islam. Madhabs made these kinds of terms to categorize ibadats. They categorized them with terms like Fard, Wajib, Sunnat, Mustahab, Mubah, etc. There is no such categorization in the Quran.

Ishtiaque Khan

I appreciate what you said. Like you, I also try to be a Puritan and to seek my source in the Koran and in the Sunnah of Rasul (peace be upon him). However, I don't think fard is the only type of Ibadah. I can give you a hint from the Koran or you can find it yourself. I found Ayats that read like "It's better for you ...", similar to Mustahab. "it's better that you don't ..." kind of like makhrooh; There are also optional prayers mentioned by the Prophet in the hadith, similar to Nafl and Sunnah. Isn't everything that the Prophet did his Sunnah, even the Fard Ibadah?

Ishtiaque Khan

While I agree that some of the terms were not used per se during the time of the prophets, but were created for better communication.