salam bro,
Page 5
The Ahl al-Sunnah, Muʿtazilah, Murji’ah, Shīʿah and Khawārij—with the exception of the Najdiyyah—all agree on the necessity of imāmah (leadership), and that obedience to an imām ʿādil (just imām) is compulsory upon the Ummah.
who are these najdiyyah?
The quote continues as:
{...However, the Najdiyyah—
a sect within the Khawarij—say that imamah is not necessary}.
So this was a sect within the Khawarij, as per Imam Dhahabi. Ofcourse, a typical jahil would think it has something to do with Muhammad bin Abdul Wahab Najdi, but the fact is this was a sect that emerged centuries before Mohammad ibn Abdul Wahab's birth.
quran [76:24]
"Therefore wait patiently for the command of your Lord, and obey not
from among them a sinner or an ungrateful one".
any thoughts if the above ayat applicable to rulers as well?
This verse and the verse before it, was for Prophet Muhammad(saws) in specific. It is not a general command.
Verily! It is We Who have sent down the Quran
to you (O Muhammad SAW) by stages. Therefore be patient (O Muhammad SAW) and submit to the Command of your Lord (Allah, by doing your duty to Him and by conveying His Message to mankind), and obey neither a sinner nor a disbeliever among them.[Quran 76: 23-24 ; Muhsin Khan and Mohammad al-Hilal]
The pronoun is also singular, it says (رَبِّكَ) RabbiKA/your(singular) Lord. If it was general then, the pronoun should have been plural. RabbiKUM(رَّبِّكُمْ).
As for obeying or following fallible rulers or scholars/people. Then this is proven from Quran. Like the verse 4:59, where in Ulil Amr are not infallible, if they were infallible then there was no scope to dispute with them and to refer back to Allah and Prophet(saws).
Secondly, We read in Quran:
And (as for) the foremost, the first of the Muhajirs and the Ansars, and those who
followed them in goodness, Allah is well pleased with them and they are well pleased with Him...(Quran 9:100).
Muhajireen and Ansar were fallible people, yet those who followed them are praised.
Moreover, Shia obey and follow their Scholars, esp. the Marja whose Taqleed they make. They are fallible.
Lastly, the verse you used cannot be used in general sense because:
حَدَّثَنَا أَحْمَدُ بْنُ مَنِيعٍ، حَدَّثَنَا زَيْدُ بْنُ الْحُبَابِ، حَدَّثَنَا عَلِيُّ بْنُ مَسْعَدَةَ، عَنْ قَتَادَةَ، عَنْ أَنَسٍ، قَالَ قَالَ رَسُولُ اللَّهِ ـ صلى الله عليه وسلم ـ : " كُلُّ بَنِي آدَمَ خَطَّاءٌ وَخَيْرُ الْخَطَّائِينَ التَّوَّابُونَ "
It was narrated from Anas that the Messenger of Allah (ﷺ) said: “Every son of Adam commits sin, and the best of those who commit sin are those who repent.’”[Sunan Ibn Majah, Book 37, Hadith 4392; Hasan]