Answer: Before answering this question, InshaAllah first we will define what is mu’allaq hadith. A mu’allaq hadith is a term derived from the verb “aalaqa” i.e. to suspend or to hang. Technically it means a hadeeth in which the beginning of its chain of narration has one or more consecutive narrators deleted. For example, in his chapter on “The obligation of Salah in clothes”, Imam Bukhari states : “And the Prophet (p.b.u.h) instructed that no naked person should walk around kaaba”..In this narration, he deleted the complete chain, including the companion up to the Prophet Muhammad [p.b.u.h].
Reasons for adding mu’allaq narrations in Saheeh-al-Bukhari
Imam Bukhari did not add mu’allaq hadith to constitute for the main proof for Islamic principle. Those narrations were used only as heading or supportive evidence. Furthermore, the great scholar, Ibn Hajar (r) wrote a book dedicated to tracking down all the mu’allaq narrations of Saheeh –al –Bukhari that he called “Taghleeq at-Ta’leeq” ie closing tightly the hanging narrations.
Indeed Allah knows the best…