Are all the hadiths mentioned in Imam adh-Dhahabi's book "Siyar A'lam an-Nubala'" authentic, or does it contain weak ones? And do you recommend reading it, or another book on biographies of Islamic figures?

It is difficult to pass judgment on the hadiths in al-Dhahabi's "Siyar A'lam al-Nubala'" and requires complete traceability. Nevertheless, al-Dhahabi is known for his extensive memorization and knowledge of hadith, and his book is one of the most important and accurate biographical works. Therefore, it is recommended to read it alongside other reliable biographical books such as "Safwat al-Safwa" and "Hilyat al-Awliya'".