Sheikhul Islam has also used weak Hadith in his book.
Shaykhul Islam’s book “Alkalimut-Tayyib” contains many weak Ahadeeth which Al-Albani (RA) has himself divided into “Saheeh Alkalimut-Tayyib” & “Da’ef Alkalimut-Tayyib” proving that it contains weak Ahadeeth in the first place
Ibn Taymiyya said in his book "al-qaida al-jaleela fit- tawwasuli wal-waseela", with commentary of Dr. Rabi'a bin Hadi 'Umayr al-Mudkhali, professor in the Islamic University of Madinah al-Munawwara, Page 162, para 478:
"But Ahmad ibn Hanbal and other scholars permitted the narration [of hadith] regarding the virtues of good what is not established [as authentic] as long as it is not known that it is a lie." (laakinna Ahmad ibn Hanbal wa ghayruh min al-'ulama jawwazu an yurwa fee fada'il al-'aamal maa lam yu'lam annahu thaabit idha lam yu'lam annahu kadhib.)
Imam Bukhari has also used weak ahadith in his book Al Adabul Mufarrad. Same is for almost all Hadith Scholar
Now a question is for all Ghair Muqalledin brothers and their supporters who are criticising Fazail e Amaal that Ok as per your Claim Sheikh zakaria is wrong ..................But
1. So is it possible that all Muhaddethin greta scholars Imam bukhari Imam Taimmiya Imam Ibne Hajar Asaqalani Rahmatullah Alaihi are wrong.???????????
2. Is it not a correct time to think that those Ghair Muqallids and their supporters who are alleging on Fazail e Amaal/ sheikh zakaria they are actually on wrong path ?????????????
As SheikhuI zakaria has said and so beautifully said:
"If the books of all these pioneers are incorrect then this incompetent one will have no worry in 'Fazaail
Hajj' being incorrect as well" ("Kutube Fazaail par ishkaaJaat awr tm kehjawaab' p 182)
For Full Hadith Discussion on all these aspect refer FOLLOWING BOOKS