Al-Tabarani and al-Hakim narrated it from `Abd Allah b. Abi Awfa. Al-Shirazi also narrated in al-Alqab from Ibn `Abbas that the Messenger of Allah – upon him blessings and peace – said, “I asked my Lord that I not marry off but to people of Paradise and that I not marry into other than people of Paradise.” Ahmad and al-Hakim narrated from al-Miswar that the Prophet said: “Fatima is a piece of my flesh, whatever distresses her distresses me and whatever delights her delights me. Verily lineages will all be cut off on the Day of Resurrection except my lineage and my line and relationships to me.” This report is fully documented in the chapter on Abu Ya`la’s Musnad.
Munawi said in Fayd al-Qadir: “It appears that this [privilege] includes whoever marries or gets married off among his descendants; this means great tidings for whoever becomes related through marriage to a Sharif or a Sharifa.”
The fact that Ahl al-Bayt spouses and in-laws are all bound for bliss is clarified by what Ibn `Asakir narrated in al-Arba`in fi manaqib Ummahat al-mu’minin, Hadith 37, from ‘Sayyidina `Ali (r) that the Prophet – upon him blessings and peace – said: “None that marries into me or that I marry into enters Hellfire.” He added, “This is a fair hadith from the Commander of the believers Abu al-Hasan `Ali b. Abi Talib – may Allah ennoble his countenance – and in this hadith there is evidence for the virtue of his brothers and sons-in-law, and this is a testimony that they are in Paradise as long as they are believers, and Allah knows best.”
Al-Harith also narrated from Muhammad b. al-Hanafiyya – in mursal mode – as did Abu Ya`la, Ibn Abi al-Dunya and Ibn `Asakir from Abu Hurayra that al-Hasan and al-Husayn wrestled in the presence of the Messenger of Allah – upon him blessings and peace – and the latter was saying, “Go, Hasan!” whereupon Fatima said: “Messenger of Allah, it seems he is more beloved to you than al-Husayn?” He replied, “Jibril is helping al-Husayn, and I love to help al-Hasan.”
[Excerpted from Musnad Ahl al-Bayt]