A tremendous benefit we learned from Shaykh Muhammad bin Aadam Al-Ithiopi, may Allah preserve him, in his classes teaching Umdatul Tafseer (summarized tafsir ibn Katheer by Ahmad Shaakir رحمهما الله). 
The Student of Knowledge should pay close attention to word selection in the Quran and how mufassirun explain these words; this will give one deeper understanding of the Book of Allah. 
For example, the Shaykh mentioned the word منيب and that the verb is أناب. However, the origin of the word is آب. 
So, why is there a noon? Where did it come from? He mentioned that the noon enters into the word in order to strengthen/emphasize the meaning.
This falls under the sarf principle:
زيادة المبنى تدل على زيادة المعنى 
Which means that whenever the construction of a word increases in letters, then so does the meaning. 
The word منيب is derived from إياب.
آب, يؤوب, إيابا. 
With the addition of the noon it becomes,
أناب, ينيب, إنابة. 
The noon in منيب enters the word in order to strengthen/emphasize the meaning of الإياب. 
And when we look to ibn Kathir’s commentary on منيب, we find that he explains this word to mean 
Which a shaddah on the Jeem:
 (الراء المهملة, الجيم المعجمة المشددة, العين المهملة)
The word رجاع is on a scale of صيغة المبالغة from the word رجع. 
Why did ibn Kathir explain منيب to mean رجاع and not just as رجع? That is because the noon in منيب strengthens/emphasizes the meaning, and because of that he also explained it in the صيغة المبالغة form. 
These subtle points can fly by your head easily when reading the Quran and tafsir. But, for the one who contemplates and reflects, he or she will benefit tremendously and will be directed to the deeper meanings of the Quran. 
*Extra Benefit* 
The words تواب أواب ثواب منيب أثاب all have the same meaning. Same goes for the words تاب, ثاب, meaning عاد. 
مثلا: ثاب فلان إلى الله. أي:عاد ورجع إلى طاعته.
Shaykh Muhammad حفظه الله then advised to return back to Tahdheeb al-Lugha for more benefit.
17th of Rabee’ al-Awwal, 1438