Imam Sadiq (peace be upon him): Abu Amr al-Zubayri said: I said to him, "Tell me about calling to Allah and jihad in His path — is this [calling and jihad] restricted to a group for whom alone it is permissible, so that no one other than them may undertake it, or is it permissible for every monotheist who believes in His Messenger?" He said, "This matter is restricted to a group for whom alone it is permissible, and no one other than them may undertake it." I said, "Who are they?" He said, "Whoever fulfils the conditions that Allah has laid down for the mujahideen in fighting and jihad — he is the one who has been permitted to call to Allah." ... I said, "May Allah have mercy on you, make this clear to me." He said, "Allah, Blessed and Exalted, informed His Prophet (peace be upon him and his family) in His Book about the callers to Him and described the callers to Him, and He set for them ranks by which some are known through others and some are inferred from others. He, Blessed and Exalted, informed that He is the first who called to Himself and called to obedience to Him and to following His command. He began with Himself ... then secondly through His Messenger (peace be upon him and his family), and thirdly through His Book, He called to Himself. Then in His Book He mentioned those to whom permission has been given, after Him and His Messenger, to call to Him, and He said: 'There must be from among you a group who call to good, and enjoin what is right and forbid what is wrong! And it is they who are the successful.' (Al Imran/104) Then He informed about this group and who they are from, [saying] that they are from the descendants of Ibrahim (peace be upon him) and Ismail (peace be upon him), the very ones about whom He informed in His Book that He has removed impurity from them and purified them with a thorough purification. ... Then He mentioned the followers of the Prophet and the followers of this group (the Ahl al-Bayt (peace be upon them)) whom Allah described as those who enjoin the good and forbid the wrong and made them callers to Himself and permitted them to call to Him, and He said: 'یا أَیُّهَا النَّبِیُّ حَسْبُکَ اللهُ وَ مَنِ اتَّبَعَکَ مِنَ الْمُؤْمِنِینَ [O Prophet! Allah and the believers who follow you are sufficient for your support (rely on them alone)!]' (Anfal/64) Then, describing these believers, He said: 'مُحَمَّدٌ رَسُولُ اللَّهِ وَ الَّذِینَ مَعَهُ أَشِدَّاءُ عَلَی الْکُفَّارِ رُحَماءُ بَیْنَهُمْ تَراهُمْ رُکَّعاً سُجَّداً یَبْتَغُونَ فَضْلًا مِنَ اللهِ وَ رِضْواناً سِیماهُمْ فِی وُجُوهِهِمْ مِنْ أَثَرِ السُّجُودِ ذلِکَ مَثَلُهُمْ فِی التَّوْراةِ وَ مَثَلُهُمْ فِی الْإِنْجِیلِ [Muhammad is the Messenger of Allah, and those who are with him are stern against the disbelievers and merciful among themselves. You see them constantly bowing and prostrating; they always seek Allah's bounty and His pleasure. Their sign is on their faces from the trace of prostration. This is their description in the Torah and their description in the Injil.]' (Fath/29) And He said: 'یَوْمَ لا یُخْزِی اللهُ النَّبِیَّ وَ الَّذِینَ آمَنُوا مَعَهُ نُورُهُمْ یَسْعی بَیْنَ أَیْدِیهِمْ وَ بِأَیْمانِهِمْ [On the day when Allah will not humiliate the Prophet and those who believed with him — while their light runs before them and on their right.]' (Tahrim/8), whose addressees are these very believers, and He said: 'قَدْ أَفْلَحَ الْمُؤْمِنُونَ [Successful indeed are the believers].' Then He set out their (inner) beauties and described them, so that no one would covet joining them except those who are of them; so in setting out their (inner) beauty and describing them He said: 'قَدْ أَفْلَحَ المُؤْمِنُونَ، الَّذِینَ هُمْ فِی صَلاتِهِمْ خاشِعُونَ، وَ الَّذِینَ هُمْ عَنِ اللَّغْوِ مُعْرِضُونَ، وَ الَّذِینَ هُمْ لِلزَّکاةِ فاعِلُونَ، وَ الَّذِینَ هُمْ لِفُرُوجِهِمْ حافِظُونَ، إِلَّا عَلی أَزْواجِهِمْ أَوْ ما مَلَکَتْ أَیْمانُهُمْ فَإِنَّهُمْ غَیْرُ مَلُومِینَ، فَمَنِ ابْتَغی وَراءَ ذلِکَ فَأُولئِکَ هُمُ العادُونَ، وَ الَّذِینَ هُمْ لِأَماناتِهِمْ وَ عَهْدِهِمْ راعُونَ، وَ الَّذِینَ هُمْ عَلی صَلَواتِهِمْ یُحافِظُونَ، أُولئِکَ هُمُ الْوارِثُونَ، الَّذِینَ یَرِثُونَ الْفِرْدَوْسَ هُمْ فِیها خالِدُون [Successful indeed are the believers, those who are humble in their prayers, and those who turn away from vain talk, and those who pay zakat, and those who guard their private parts — except from their spouses or those whom their right hands possess, for they are not blameworthy; but whoever seeks beyond that, they are the transgressors — and those who keep their trusts and covenants, and those who guard their prayers. Those are the inheritors, who will inherit Paradise; they will abide therein forever].'"