The Prophet ﷺ said, "You are living in an age whose scholars are many and whose preachers are few. Whoever abandons a tenth of what he knows in this age has gone astray," or he said, "has perished. A time will come upon people when their scholars will be few and their preachers many. Whoever holds fast to a tenth of what he knows in that age will be saved."
أن النبي ﷺ قال: إنكم في زمان علماؤه كثير، خطباؤه قليل، من ترك فيه عشير ما يعلم هوى، أو قال: هلك، وسيأتي على الناس زمان يقل علماؤه ويكثر خطباؤه، من تمسك فيه بعشير ما يعلم نجا.
Ahmad narrated it (21372) from Muammal (he is Ibn Ismail), who said, Hammad narrated to us, who said, Hajjaj Aswad narrated to us, who said, "I heard Abu Siddiq narrating to Thabit Banani, from a man, from Abu Dharr," and he mentioned it. Its isnad contains an unnamed man, and Muammal bin Ismail has poor memory. There is disagreement regarding him about including this unnamed man or omitting him. Ahmad narrated it from him with the man included. Ishaq (that is, Ibn Rahawayh) narrated it from him with the man omitted (that is, from Abu Siddiq from Abu Dharr directly). Bukhari mentioned this narration in Tarikh al-Kabir (2/374).Isa bin Yunus narrated it, from Hajjaj bin Abu Ziyad Aswad, from Abu Siddiq or Abu Nadra, Hajjaj being uncertain which, from Abu Dharr. Abu Dharr Harawi recorded his narration in Dhamm Kalam (100), and Bukhari in Tarikh al-Kabir (2/374).Hajjaj's uncertainty causes no harm, for Abu Siddiq and Abu Nadra are both trustworthy. The real difficulty lies in whether they met Abu Dharr, since he died in the year 32 AH, while Abu Siddiq and Abu Nadra died in the year 108 AH. The gap between their deaths is 76 years, which does not preclude their having met Abu Dharr.As for what Alai mentioned in Jami Tahsil (p. 277), "He narrated from Ali and Abu Dharr, from among the early Companions," and that this is mursal, as he stated in Tahzib, I say, I did not find this statement in Tahzib Kamal, and likewise Abu Zura Iraqi said, "I did not find it therein." So the default assumption is that the chain is connected unless he is a mudallis, so the isnad of the hadith is hasan because of Muammal bin Ismail, since there is supporting evidence for it, which is as follows.Along similar lines is what was narrated from Abu Hurairah as a marfu hadith, "You are in a time when whoever among you abandons a tenth of what he is commanded perishes, then a time will come when whoever among them acts upon a tenth of what he is commanded is saved." Tirmidhi (2267) and Ibn Adi (7/2483) both narrated it, both by way of Naeem bin Hammad, who said, Sufyan bin Uyayna narrated to us, from Abu Zinad, from Araj, from Abu Hurairah, and he mentioned it.Tirmidhi said, "We do not know this hadith except through the narration of Naeem bin Hammad, from Sufyan bin Uyayna." I say, Naeem bin Hammad has poor memory, and many hadiths have been criticized as denounced coming from him, including this hadith. Ibn Abu Hatim mentioned Naeem bin Hammad's route to his father, who said, "This is, in my view, an error. Jareer and Musa bin Ayun narrated it, from Layth, from Maruf, from Hasan, from the Prophet ﷺ, as mursal." Ilal (2794).Nasai said, "This is a munkar hadith." Ibn Jawzi related this from him in Ilal Mutanahiya (1425). This means that the correct version is the mursal narration of Hasan, and raising it to the level of marfu is an error.