Ocean Of Knowledge

It is said: “العلم بحر لا ساحل له – Knowledge is an Ocean that has no Coast.”

The Tree of Knowledge has 100’s of branches, like: ‘Tafsir’, ‘Hadith’, ‘Fiqh’, ‘Qira’aat’, ‘Lugha’, ‘Aqidah’, ‘Sirah’, ‘Finance’, etc.

Some people think: a scholar knows it all …
No, a person may be a scholar in one branch of knowledge and still be completely unaware about other branches.
This does not diminish his status in our eyes.
A Muhadith may not be a Faqih (jurist), so we should not ask him about Fiqh.
Similarly, many fuqaha based their rulings on weak and fabricated narrations, because they did not specialise in ‘ilm al-Hadith’.
A scholars who specialise in all the branches is rare.
Many scholars criticized other fellow scholars, for discussing topics outside their area of expertise, even though they were all scholars in their own respective fields.

For example, Ibn Hajar al-‘Asqalani criticized Imam al-Kirmani on a particular issue, saying:

قال الحافظ ابن حجر رحمه الله في حق الكرماني رحمه الله في الفتح (3/ 584).
إذا تكلم المرء في غير فنه أتى بهذه العجائب.
“When a person speaks outside of his area of expertise (science), he comes up with strange conclusions like this one.”

[“Fath al-Bari”, 3/584].