Imam Abu bakr Mohammad bin al Hasan al Ajurri رحمہ اللہ writes under the chapter "Virtues of Hassan and Hussain رضیﷲ عنهما" which he compiled in his book "As Shariah":
اعْلَمُوا رَحِمَنَا اللَّهُ وَإِيَّاكُمْ: أَنَّ الْحَسَنَ وَالْحُسَيْنَ رَضِيَ اللَّهُ عَنْهُمَا خَطَرُهُمَا عَظِيمٌ، وَقَدْرُهُمَا جَلِيلٌ، وَفَضْلُهُمَا كَبِيرٌ، أَشْبَهُ النَّاسِ بِرَسُولِ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ خَلْقًا وَخُلُقًا الْحَسَنُ وَالْحُسَيْنُ رَضِيَ اللَّهُ عَنْهُمَا، هُمَا ذُرِّيَّتُهُ الطَّيِّبَةُ الطَّاهِرَةُ الْمُبَارَكَةُ، وَبَضْعَتَانِ مِنْهُ، أُمُّهُمَا فَاطِمَةُ الزَّهْرَاءُ، مُهْجَةُ رَسُولِ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ، وَبَضْعَةٌ مِنْهُ، وَأَبُوهُمَا أَمِيرُ الْمُؤْمِنِينَ عَلِيُّ بْنُ أَبِي طَالِبٍ رَضِيَ اللَّهُ عَنْهُ، أَخُو رَسُولِ رَبِّ الْعَالَمِينَ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ، وَابْنُ عَمِّهِ، وَخَتَنُهُ عَلَى ابْنَتِهِ، وَنَاصِرُهُ وَمُفَرِّجُ الْكَرْبَ عَنْهُ، وَمَنْ كَانَ اللَّهُ وَرَسُولُهُ لَهُ مُحِبِّينَ
Be informed! may Allah have mercy upon you and us, that the virtues of Saydna Hasan and Hussain رضیﷲ عنهم is great and their status is high, with best of the ranks and they resembled the most to the Prophet Mohammad ﷺ with physical appearance as well as character and behaviour, they are the honorable offsprings of Prophet ﷺ, they are the part of his life, their mother, Sayyidah Fatima رضیﷲ عنها was the dearest daughter of the Prophet ﷺ and a part of his life, their father, Saydna Ali ibn Abi Talib رضیﷲ عنه was paternal cousin of Prophet of Allah عزوجل and the son of Prophet's Uncle and he was the son in law of Mohammad ﷺ, and he was helper of Mohammad ﷺ as he used to remove the sadness and trouble of Rasool ﷺ and he was the one who's loved by Allah and his Rasool ﷺ,
فَقَدْ جَمَعَ اللَّهُ الْكَرِيمُ لِلْحَسَنِ وَالْحُسَيْنِ رَضِيَ اللَّهُ عَنْهُمَا الشُّرَفَ الْعَظِيمَ، وَالْحَظَّ الْجَزِيلَ مِنْ كُلِّ جِهَةٍ، رَيْحَانَتَا رَسُولِ اللَّهِ صَلَّى اللهُ عَلَيْهِ وَسَلَّمَ، وَسَيِّدَا شَبَابِ أَهْلِ الْجَنَّةِ،۔
Allah عزوجل gathered all the virtues and ranks of Hasan and Hussain رضیﷲ عنهم and blessed them with his best of the qualities, they both are beautiful flowers of the beautiful garden of Mohammad ﷺ and they both are the leaders of youth in Jannah.
وَسَنَذْكُرُ مَا حَضَرَنِي ذِكْرُهُ بِمَكَّةَ مِنَ الْفَضَائِلِ؛ مَا تُقَرُّ بِهَا عَيْنُ كُلِّ مُؤْمِنٍ مُحِبٍّ لَهُمَا، وَيُسْخِنُ اللَّهُ الْعَظِيمُ بِهَا عَيْنَ كُلِّ نَاصِبِيٍّ خَبِيثٍ، بَاغِضٍ لَهُمَا أَبْغَضَ اللَّهُ مَنْ أَبْغَضَهُمَا».
I will indeed talk about the narrations which I have in regards to them from Holy Makkah and by this it would become coolness of the eyes for every believer who possess love in their heart for them and with the virtues of them Allah will burn the eyes of every khabees Nasibi (The one who hates Ahle bayt) who have hate in their hearts for Hassan and Hussain رضیﷲ عنهم.
[Kitab as Shariah, Book of Virtues, Hasan and Hussain رضیﷲ عنهم pg. 664, 3/242]
~ Translated from Alkaseri Mohsin
