وَ قَالَ الْعَلَّامَةُ رَوَّحَ اللهُ رُوحَهُ فِيْ كِتَابِ كَشْفِ الْحَقِّ رَوَى الْجُمْهُورُ فِيْ الصَّحِيحَيْنِ وَ اَحْمَدُ بْنُ حَنْبَلٍ فِيْ مُسْنَدِهِ وَ الثَّعْلَبِيُّ فِيْ تَفْسِيرِهِ عَنِ ابْنِ عَبَّاسٍ قَالَ لَمَّا نَزَلَ قُلْ لا اَسْئَلُكُمْ عَلَيْهِ اَجْرًا اِلَّا الْمَوَدَّةَ فِيْ الْقُرْبى قَالُوا يَا رَسُولَ اللهِ مَنْ قَرَابَتُكَ الَّذِينَ وَجَبَتْ عَلَيْنَا مَوَدَّتُهُمْ قَالَ عَلِيٌّ وَ فَاطِمَةُ وَ ابْنَاهُمَا
Allamah Hilli (r.a.) records in his book Kashf al-Haqq, “The majority of Muslims have narrated in their two Saheeh (Bukhari and Muslim), Ahmad Ibn Hanbal in his Musnad, al-Tha’labi in his exegesis from Ibn Abbas that when the verse, ‘Say (O Prophet)! I don’t ask from you any reward or wage for my efforts in Prophethood except the love of my closest family members’ (Surah Shura (42): Verse 23), they asked, ‘O Messenger of Allah! Who are your closest relatives whose love has been made obligatory upon us?’ He (peace be upon him and his holy progeny) replied, ‘Ali, Fatema and their two sons.’
Note:
This verse also indicates towards the infallibility of the Ahle Bait (peace be upon them) as not even a normal wise person will order the people to love his family/children if they are disobedient and wayward. Therefore, when Allah the High and His Messenger (peace be upon him and his holy progeny) demand the love of his progeny as reward for the efforts of his mission, then one can imagine the extent of proximity they enjoy in front of Allah the High and the sublimity of their infallibility!
References:
1. Behaar al-Anwaar, vol. 23, p. 232
2. Kashf al-Haqq, p. 175