Al-Qurtubi, as well as other scholars, said that this Ayah (2:30) proves the obligation of appointing a Khalifah to pass judgements on matters of dispute between people, to aid the oppressed against the oppressor, to implement the Islamic penal code and to forbid evil. There are many other tasks that can only be fulfilled by appointing the Imam, and what is necessary in performing an obligation, is an obligation itself. We should state here that Imamah occurs by either naming a successor, as a group among Ahl As-Sunnah scholars said occurred - by the Prophet - in the case of Abu Bakr, or hinting to a successor. Or, the current Khalifah names a certain person as Khalifah after him, as Abu Bakr did with `Umar. Or, the Khalifah might leave the matter in the hands of the Muslim consultative council, or a group of righteous men, just as `Umar did. Or, the people of authority could gather around a certain person to whom they give the pledge of allegiance, or they could select one among them to choose the candidate, according to the majority of the scholars.
The Khalifah must be a responsible adult Muslim male, able to perform Ijtihad (independent legal judgments), bodily able, righteous, with knowledge of warfare, politics. He also must be from the tribe of Quraysh, according to the correct view, but it is not necessary that he be from the tribe of Bani Hashim, or that he be immune from error, as the Rafidah (Shiites) falsely claim.
When the Khalifah becomes an immoral person (Fasiq), should he be impeached There is disagreement over this matter, but the correct view is that he is not to be removed, because the Messenger of Allah said,
«إِلَّا أَنْ تَرَوْا كُفْرًا بَوَاحًا عِنْدَكُمْ مِنَ اللهِ فِيهِ بُرْهَان»
(Unless you witness a clear Kufr regarding which you have clear proof from Allah. )
Does the Khalifah have the right to resign from his post There is a difference on this issue. It is a fact that Al-Hasan bin `Ali removed himself from the position of Khalifah and surrendered it to Mu`awiyah. However, this occurred because of a necessity, and Al-Hasan was praised for this action.
It is not permissible to appoint two Imams for the world or more at the same time. This is not allowed because the Messenger of Allah said,
«مَنْ جَاءَكُمْ وَأَمْرُكُمْ جَمِيعٌ يُرِيدُ أَنْ يُفَرِّقَ بَيْنَكُمْ فَاقْتُلُوهُ كَائِنًا مَنْ كَان»
(Whoever came to you while you are united and tried to divide you, then execute him, no matter who he is.)
This is the view of the majority of scholars. Imam Al-Haramayn stated that Abu Ishaq allowed the appointment of two or more Imams when the various provinces are far away from each other. However, Imam Al-Haramayn himself was indecisive about this view.
﴿وَعَلَّمَ ءَادَمَ الأَسْمَآءَ كُلَّهَا ثُمَّ عَرَضَهُمْ عَلَى الْمَلَـئِكَةِ فَقَالَ أَنبِئُونِى بِأَسْمَآءِ هَـؤُلاَءِ إِن كُنتُمْ صَـدِقِينَ - قَالُواْ سُبْحَـنَكَ لاَ عِلْمَ لَنَآ إِلاَّ مَا عَلَّمْتَنَآ إِنَّكَ أَنتَ الْعَلِيمُ الْحَكِيمُ - قَالَ يَـاءَادَمُ أَنبِئْهُم بِأَسْمَآئِهِمْ فَلَمَّآ أَنبَأَهُم بِأَسْمَآئِهِم قَالَ أَلَمْ أَقُل لَّكُمْ إِنِّي أَعْلَمُ غَيْبَ السَّمَـوَاتِ وَالاٌّرْضِ وَأَعْلَمُ مَا تُبْدُونَ وَمَا كُنتُمْ تَكْتُمُونَ ﴾
(31. And He taught Adam all the names (of everything), then He showed them to the angels and said, "Tell Me the names of these if you are truthful.'') (32. They (angels) said: "Glory is to You, we have no knowledge except what you have taught us. Verily, You are the Knower, the Wise.'') (33. He said: "O Adam! Inform them of their names,'' and when he had informed them of their names, He said: "Did I not tell you that I know the Ghayb (unseen) in the heavens and the earth, and I know what you reveal and what you have been concealing'')