Hadith of the two weighty things went to Zayd b.Arqam, one of the transmitters of the standard Ghadir Khumm. Zayd said to them that he has "forgotten some [of what he had heard from the prophet]" but he began to recite Hadith al-Thaqalayn for them as words that heard from prophet in The event of Ghadir Khumm. As the Allameh Tabataba'i said, some points can be driven from this hadith such as "the Holy Quran will remain until the day of Judgment, the progeny of the Mohammad prophet will remain". There will be any period of time that Shia Imam doesn't exist to guide Muslims. All
Hadith of the Ark follows: Behold! The similitude of my Ahlul Bayt, is like that of the Ark of Noah: The one who embarks it, will have saved himself, and the one who turns away from it, is doomed. Many Sunni books narrate this Hadith. Some significant Sunni books that narrate this Hadith are: Al-Hakim al-Nisaburi, one of the greatest Sunni scholars, narrated this hadith as authentic (sahih) in his Mustadrak. Al-Heithami in his book ("written against Shia") states: By many narrations of this hadith which strengthen each other;""certainly Ahl al-Bayt are like the Ark of Noah, saved Whoever boarded"", and in Sahih Muslim