We find this narration on some forums;
On the authority of Zaid bin Aslam Al-Adawi (RA) from his father (RA), the Messenger of Allah (SAW) said, “Jihad will always feel sweet and beautiful as long as rain still falls from the sky. Yet there will come upon mankind an era, when at that time, the people who understand the Qur’an (scholars) from amongst them say, ‘This era is not the time of jihad.’ Whoever encounters those days, then let him know that those are the best times for Jihad.” The Companions asked: “O Messenger of Allah (SAWS), will anyone really say that?” He (SAWS) replied: “Yes, he upon whom is the curse of Allah, His Angels and all of mankind.” [Ibn Asakir transmitted it. (Mashari- ul-Ashwaq by Ibn Nuhaas, Vol. 1, P. 110)]
With the particular wording quoted and with complete chain it is found in Sunan Al-Waridah fil Fitan by Al-Dani Hadith 373 (Makteb Al-Shamela ed.)
Wording as found in Al-Dani’s book;
لا يزال الجهاد حلوا أخضر ما قطر القطر من السماء ، وسيأتي على الناس زمان يقول فيه قراء منهم : ليس هذا زمان جهاد ، فمن أدرك ذلك الزمان فنعم زمان الجهاد » قالوا : يا رسول الله ، واحد يقول ذلك ؟ فقال : « نعم ، من عليه لعنة الله والملائكة والناس أجمعين
In its edition with research published by Darul Aasimah p. 751 Hadith 371 the researcher Dr. Razaullah b. Muhammad b. Idris Mubarakpuri writes, “This is Mursal and in it (means its chain) is Abdul Rahman bin Zaid bin Aslam and he is Da’if.”
In Ibn Asaakir’s Tarikh Damishq (43/347) it is different except the initial words and is narrated with a different chain from Anas (RA).
As found in Ibn Asaakir’s Tarikh Damishq;
لا يزال الجهاد حلوا خضرا ما امطرت السماء وأنبتت الأرض وسينشو نشو من قبل المشرق يقولون لا جهاد ولا رباط أولئك هم وقود النار بل رباط يوم في سبيل الله خير من عتق ألف رقبة ومن صدقة أهل الأرض جميعا
Hafiz Suyuti quotes the same in Jami’ Al-Kabir Hadith 1818 and says;
ابن عساكر وضعفه عن أنس
‘Ibn Asaakir [narrated it] and its weak from Anas.’
Same is written in Kanzul Ummal Hadith 10742.
Perhaps the above detail is the reason narration is not found in Tahdhib of the Imam Ibn Nuhas’ book Mashari- ul-Ashwaq ilaa Masaari’-ul-Ushaaq by Dr. Salaah Abdul Fattah Al-Khalidi
Note: Its only about status of a narration. There are countless narrations about the greatness of Jihad and in condemnation of those who refrain from it.
And Indeed Allah knows the best!