HAZRAT ZAID BIN ARQAM (RAZE ALLAH O TALLAH) reported Prophet Muhammad(SAW)
i am leaving among u something of such a nature that if u lay hold of it u will never go astray after i am gone
,Allah's book n AHl e bait .someone asked who r Ahl e bait he replied
AAL E ALI,AAL E JAAFAR,AAL E AQEEL n AAL E ABBAS.
(PRECEPT NO 6321 SAHEE MUSLIM).
similarly in SURAH ALAHZAAB ALLAH says
O Prophet!sayto ur wives:if it be that u desire the life of this world n its glitter,then come !i will provide for ur enjoyment
n set u free in a handsome manner(28)
but if u seek Allah n His messenger n the home of hereafter ,verily Allah has prepared for the well doers amongst u a great reward(29).
O Wives of the prophet!if any of u were guilty of evident unseemly conduct ,the punishment would be doubled to her n that is easy for ALLAH(30)
but any of u that is devout in the service of Allah n His messenger ,n works righteousness,to her shall we grant her reward twice ,n we have prepared for her a generous sustenance(31)
O wives of the Prophet!u r not like any of the other women if u do fear Allah be not too complaisant of speech lest one in whose heart is a disease should be moved with desire but speak a speech that is just(32)
n saty quietly in ur houses n make not a dazzling display,like that of the former times of ignorance n establish regular prayer n give zakat n obey Allah n His mesenger.and Allah only wishes to remove all abomination from u,these r ur Ahl e Bait O Prophet n ALLAH want to make them pure n spotless(33).
these verses of Quran show that all the wives of Hazrat Muhammad were also included in Ahl e Bait.

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Allah is He,than Whom there is no God ;the Sovereign,the Holy One,the Source of Peace(n Perfection),the Guardian of Faith,the Preserver of Safety,the Exalted in Might,the Irresistible,the justly Proud glory to Allah!(High is He)above the partners they attribute to Him.(Surah e Hashar,verse #23)