None of the hadiths about the timing of cupping are saheeh
Question

Is cupping on Saturday or Friday makrooh if it happens to be the 17th, 19th or 21st, as mentioned in the hadith “Do not do cupping on Wednesdays, Fridays, Saturdays or Sundays”? This has become something that is regarded as important among the Muslims in Britain. I hope that you can explain: are these hadiths da‘eef or saheeh?
Praise be to Allah.Firstly: 
There are many hadiths from the Prophet (blessings and peace of Allah be upon him) about the timing of cupping, which refer to his words or actions. They may be divided into two categories: 
1.
Hadiths which state the preferred days for cupping, which are the seventeenth – especially if it happens to be a Tuesday – the nineteenth and the twenty-first of the lunar month, and Mondays and Thursdays among the days of the week. 
2.
Hadiths which forbid cupping on certain days of the week, namely Saturday, Sunday and Tuesday. There are also hadiths which encourage doing cupping on Tuesdays, Wednesdays and Fridays. 
Most of the leading scholars have stated that all the hadiths in these two categories are da‘eef and not one of them is soundly narrated from the Prophet (blessings and peace of Allah be upon him). There follow some of their statements: 
1.Imam Maalik was asked about cupping on Saturdays and Wednesdays, and he said:
There is nothing wrong with that; there is no day on which I have not had cupping done, and I do not regard any of that as makrooh. End quote. 
Al-Muntaqa Sharh al-Muwatta’ (7/225), quoted from al-‘Atabiyyah
 It says in al-Fawaakih ad-Dawaani (2/338), which is a Maaliki book:
(Cupping is permissible) on all days, even Saturdays and Wednesdays. In fact Maalik deliberately used to have cupping done on those days, and he did not regard any kind of medical treatment as makrooh on those two days. The hadiths which warn against cupping on those days were not regarded as saheeh by Maalik (may Allah be pleased with him). End quote. 
2.‘Abd ar-Rahmaan ibn Mahdi (may Allah have mercy on him) said:
There is no saheeh report from the Prophet (blessings and peace of Allah be upon him) concerning the timing of cupping; however he enjoined doing it. End quote. 
Narrated by Ibn al-Jawzi in al-Mawdoo‘aat (3/215) 
3.Al-Khallaal narrated from Imam Ahmad that the hadith is not proven.
Narrated by Ibn Hajar in Fath al-Baari (10/149) 
4.Al-Bardha‘i said:
I saw Abu Zar‘ah not confirming any hadith about cupping being makrooh on a particular day or being mustahabb on a particular day. End quote. 
Su’aalaat al-Bardha‘i (2/575) 
5.Al-Haafiz Ibn Hajar said, commenting on the words of Imam al-Bukhaari, “Chapter on what time cupping should be done, and Abu Moosa had cupping done at night”
Concerning the suitable times for cupping, there are hadiths none of which meet his (al-Bukhaari’s) conditions. It is as he was indicating that it may be done when needed, and it is not restricted to one time rather than another, because he mentioned cupping being done at night. End quote. 
Fath al-Baari (10/149) 
6.Al-‘Aqeeli (may Allah have mercy on him) said:
No report has been proven sound about this matter – i.e., the best day for cupping. End quote. 
Ad-Du‘afa’ al-Kabeer (1/150) 
7.Ibn al-Jawzi (may Allah have mercy on him) included some chapters in his book al-Mawdoo‘aat (3/211-215) in which he compiled these hadiths on this topic, after which he said:
None of these hadiths are saheeh. End quote. 
8.Imam an-Nawawi (may Allah have mercy on him) said:
To sum up, nothing is proven about the prohibition on cupping on particular days. End quote. 
al-Majmoo‘ (9/69). 
However, an-Nawawi classed as hasan the hadith about doing cupping on the seventeenth, nineteenth and twenty-first (of the lunar month). 
Al-Haafiz Ibn Hajar (may Allah have mercy on him) said: 
None of these hadiths is saheeh. End quote. 
Fath al-Baari (10/149) 
Secondly: 
Many of the scholars regarded it as mustahabb to do cupping on the seventeenth, nineteenth and twenty-first of the lunar month, based on a number of points of evidence: 
1.That was narrated with saheeh isnaads from the Sahaabah (may Allah be pleased with them):
It was narrated that Anas ibn Maalik (may Allah be pleased with him) said: 
The Companions of the Prophet (blessings and peace of Allah be upon him) used to do cupping on the odd-numbered days of the month. 
Narrated by at-Tabaraani in Tahdheeb al-Athaar (no. 2856). He said: Muhammad ibn Bashshaar told us: Abu Dawood told us: Hishaam told us, from Qataadah, from Anas. 
This is a saheeh isnaad. Abu Zar‘ah said: The best report concerning it is the hadith of Anas: The companions of the Messenger of Allah (blessings and peace of Allah be upon him) used to do cupping on the seventeenth, nineteenth and twenty-first.
Su’aalaat al-Bardha‘i (2/757) 
After the report mentioned above, at-Tabari also narrated that Rafee‘ Abu’l-‘Aaliyah said: They used to regard it as mustahabb to do cupping on odd-numbered days of the month. 
It was narrated that Ibn ‘Awn said: Some of his companions used to advise doing cupping on the seventeenth and nineteenth. Ahmad said: Sulaym said: Hishaam told us, from Muhammad, that he added: and the twenty-first. 
Perhaps the Sahaabah learned that from the Prophet (blessings and peace of Allah be upon him), which gives the impression that these hadiths were originally marfoo‘. In fact some of the scholars are of the view that some of the marfoo‘ hadiths concerning that are qawiy, such as Imam at-Tirmidhi when he narrated the hadith of Anas ibn Maalik (may Allah be pleased with him) who said: The Messenger of Allah (blessings and peace of Allah be upon him) used to have cupping done on the two veins at the side of the neck and between the shoulder blades, and he used to have cupping done on the seventeenth, nineteenth and twenty-first. (No. 2051). He (at-Tirmidhi) said: A hasan hadith. 
Some of the later scholars did likewise, such as as-Suyooti in al-Haawi li’l-Fataawa (1/279-280); Ibn Hajar al-Haytami in al-Fataawa (4/351); and Shaykh al-Albaani in as-Silsilah as-Saheehah (no. 622, 1847). 
However the texts that we have mentioned above from the imams, which described the marfoo‘ report as da‘eef, are more likely to be correct. 
2.That is also supported from a medical point of view:
Al-‘Allaamah Ibn al-Qayyim (may Allah have mercy on him) said – after narrating the hadiths that speak of doing cupping on the seventeenth, nineteenth and twenty-first –:
These hadiths are in accordance with what is agreed upon among doctors, which is that cupping in the second half and third quarter of the month is more beneficial than in the first half and last quarter.
However, if it is used when there is a need for it, then it is beneficial at any time, whether that is at the beginning of the month or the end.
Al-Khallaal said: ‘Usmah ibn ‘Isaam told me: Hanbal told us: Abu ‘Abdullah Ahmad ibn Hanbal used to have cupping done at any time he felt the need, at any hour of the day. End quote.
Zaad al-Ma‘aad (4/54)
But with regard to choosing days of the week for cupping, nothing is proven concerning that from a medical point of view, as far as we know, although there are reports from some of the Sahaabah concerning that. It is proven from Imam Ahmad that he used to avoid cupping on Saturdays and Wednesdays. That was narrated by Ibn al-Qayyim in Zaad al-Ma‘aad (4/54) from al-Khallaal.
Ibn Muflih (may Allah have mercy on him) said:
Cupping is makrooh on Saturdays and Wednesdays. This was stated in a report of Abu Taalib and a number of others. Ahmad added the report of Muhammad ibn al-Hasan ibn Hassaan. They also mentioned Fridays. This is what was stated definitively in al-Mustaw‘ab and elsewhere.
Al-Marwadhi said: Abu ‘Abdullah used to have cupping done on Sundays and Tuesdays.
Al-Qaadi said: It is clear that Sundays and Tuesdays are preferred, and Saturdays and Wednesdays are disliked. Nothing was said about Fridays. End quote.
It was narrated from az-Zuhri in a mursal report: “Whoever has cupping done on a Saturday or a Wednesday, and is afflicted with leprosy, let him blame no one but himself.”
This was mentioned by Ahmad and quoted as evidence. Abu Dawood said: Its isnaad is not saheeh.
Al-Bayhaqi said that it was regarded as mawsool by more than one scholar, but he regarded that as incorrect. Rather it is munqati‘ (interrupted). End quote.
It was narrated by Abu Bakr ibn Abi Shaybah with his isnaad from Mak-hool in a mursal report.
Ahmad was told that a man was treated with cupping on a Wednesday and he took the hadith lightly and said: What is this hadith? Then he was afflicted with leprosy. Ahmad said: No one should take the hadith lightly. This was narrated by al-Khallaal.
It was narrated from Ibn ‘Umar in a marfoo‘ report: “On Friday there is an hour when no one is treated with cupping but he is exposed to a disease from which there is no healing.”
Narrated by al-Bayhaqi with a hasan isnaad. It includes ‘Ataaf ibn Khaalid, in whom there is some weakness. End quote.
Al-Adaab ash-Shar‘iyyah by Ibn Muflih (3/333)
Something similar was also narrated from Ibn Ma‘een and ‘Ali ibn al-Madeeni.
And Allah knows best.