All the Hadith experts are in consensus that in matters of excellence (Fadhaail), a weakly authenticated Hadith is to be acted upon. Thus, Imam Abu Zakariyya Mohiuddin Yahya bin Sharaf Nawawi (May Allah shower His mercy on him) has clarified this at various places in his writings:
Translation: The scholars of the Ummah all hold that it is permissible to acts upon a weakly authenticated Hadith in matters of excellence. (Sharh Al Arba‘een An Nawawiyya, Muqaddima, Al Majmu’ Sharh Ul Muhadhhab)
In spite of weakly-authenticated Hadith being accepted by the Hadith experts, rejecting the Hadith which mention the excellence of the 27th night of Rajab by simply labeling them as weakly-authenticated (Dha’eef) isn’t just at all. Honesty and impartiality demand that even the weak Hadith about the 27 night of Rajab ought to be acted upon, as per the clarification of the Hadith-experts.
Abul Hasanaat Islamic Research Center 