1. Science of Hadith-5

2. Hassan Hadith
الحديث الحسن: هو ما اتصل سنده بنقل العدل خفيف الضبط من غير شذوذ و لا علة
Hassan Hadith fulfills all of the conditions (1) to (5), except that condition 3 which is precision is met to a lesser degree.
One or more of its narrators does not have an excellent level of precision.
Therefore, the isnaad falls from the standard of Al-Saheeh to that of being hassan.

3. Hassan Hadith, continued
The ruling of Hassan Hadith.
It is the same as for Al-Hadith Al-Saheeh, it is accepted, but if there is a contradiction between the two of them concerning a particular subject , then the Saheeh takes precedence over Alhassan.
What does “Saheeh al-isnaad” mean?
Is it the same like “ Hadith Saheeh”?
The answer is no. A hadith whose isnaad is saheeh , may contradict something more authentic or still have a hidden defect. However, the term hadith saheeh means that all five conditions have been met.

4. Hassan Saheeh (حسن صحيح)
Some scholars of hadith used the term Hassan-Saheeh.
Imam At-Tirmithee, is one of them. So what does this term mean?
This was explained by ibn Hajar, and is also the opinion of Al-Imam Asuyooti and ibn Otheimeen.
(1) If the hadith has two isnaads or more, then one isnaad is saheeh and the other is hassan.
(2) the 2nd option, if the hadith has only one isnaad, then it is saheeh for some scholars and hassan for other scholars.
Example: ”لولا أن أشق على أمتي لأمرتهم بالسواك عند كل صلاة“
“ If it was not inconvenient, I would have commanded my Ummah to use the Siwak at every prayer”
This Hadith was collected by Imam Bukhari and Muslim through one chain of narration that is authentic, and was collected by Imam Tirmithee through Mohamed ibn Amr whose level of precision is a matter of controversy. Some scholars consider his hadith as saheeh and others believe that his hadith should be only hassan.

5. Books of Hassan Hadith
No one has dedicated a singular book for Hassan Hadith only, like they did with Al-Hadith As-Saheeh.
There are books which contain a big number Al-ahadeeth Alhassanah, like :
(1) Jaami’ At-Tirmithee written by Imam Abi Isa’ Mohamed bin Isa’ At-Tirmithee
(p. 279H)
(2) Sunan Abi Dawood written by Suleiman bin Alsha’th As-Sejestani ( P. 275H)
When Abu Dawood (May Allah have mercy on him) finished his book the Sunan, he wrote a letter to the scholars of Mecca explaining to them his methodology in collecting these ahadeeth in his book. He mentioned that he collected Alhadith as-saheeh, and the one that is close to it in regards to its conditions, and if there is a hadith that does not meet these conditions, he promised that he will talk about it and mention its state of weakness.
(3) Sunan Ad-Daraqutni written by Abi Alhassan Ali bin Omar Ad-Daraqutni (p. 385 H)

6. The Rejected Report (الخبر المردود)
There are many types, but they are mostly due to one of two reasons:
(1) something is missing in the isnaad
(2) Narrators being unacceptable
The rejected report is Da’aeef.
In Arabic, Da’aeef means opposite of Strong.
In the Science of Hadith, It is the one that does not fulfill the conditions of the hasan Hadith.

7. Classes of Hadith Da’eef
(1) Da’eef (weak)
(2) Da’eef jiddan (Very weak)
(3) Waahee (baseless)
(4) munkar ( Weak and contradicting something more authentic)
(5) Mawdoo’ (fabricated)

8. Ruling regarding acting on the Da’eef Hadith
Some scholars like Imam al-Bukharee, Muslim, Ibn Ma’een and ibn Hazm hold that the weak hadeeth is rejected and not to be acted upon, as it does not provide any knowledge.
Other scholars, are of the opinion that it may acted upon if some conditions are met, and it is only in the area of Faza’l Alamaal.
Imam ibn Hajjar explains these conditions as follows:
1) the weakness is not severe.
2)That is falls under a well established general rule in the Sharee’ah.
3) It should not be considered as an established hadith from the prophet (peace be upon him.