The words of Anas (may Allah be pleased with him) regarding the slave women of ‘Umar: “They used to serve us bare-headed”
Question

I have been debating with the Shi‘ah for a while, and praise be to Allah I refuted all their specious arguments. But I could not find any answer to this specious argument, so I hope that you can explain to me what it means, if the report is sahih, and refute them.
This is the specious argument:
Then it was narrated via Hammaad ibn Salamah: Thumamah ibn ‘Abdillah ibn Anas told me, from his grandfather Anas ibn Malik, who said: “The slave women of ‘Umar (may Allah be pleased with him) used to serve us bare-headed, with their breasts jiggling.” I say: Its isnaad is jayyid (good) and its narrators are all trustworthy (thiqah) except the shaykh of al-Bayhaqi, Abu’l-Qasim ‘Abd ar-Rahman ibn ‘Ubaydillah al-Harbi, who is sincere (saduq), as al-Khatib (10/303) said. Al-Bayhaqi said, after quoting it: The reports from ‘Umar ibn al-Khattab (may Allah be pleased with him) regarding that are sahih.
Praise be to Allah.Firstly:
Al-Bayhaqi (may Allah have mercy on him) said in his Sunan (3222):
Abu’l-Qasim ‘Abd ar-Rahman ibn ‘Ubaydillah al-Hirafi told us in Baghdad: ‘Ali ibn Muhammad ibn az-Zubayr al-Kufi told us: al-Hasan ibn ‘Ali ibn ‘Affan told us: Zayd ibn al-Hubab told us, from Hammad ibn Salamah, who said: Thumamah ibn ‘Abdillah ibn Anas told me, from his grandfather Anas ibn Malik, who said: “The slave women of ‘Umar (may Allah be pleased with him) used to serve us bare-headed, with their hair coming down to their breasts.”
This is a hasan isnad. Al-Albani (may Allah have mercy on him) said:
Its isnad is jayyid (good) and its narrators are all trustworthy (thiqah) except the shaykh of al-Bayhaqi, Abu’l-Qasim ‘Abd ar-Rahman ibn ‘Ubaydillah al-Harbi, who is sincere (saduq), as al-Khatib said."(Irwa’ al-Ghalil  6/204).
It was narrated by Yahya ibn Salam in his Tafsir (1/441): Hammad and Nasr ibn Tarif told me, from Thumamah ibn Anas ibn Malik, from Anas ibn Malik, who said: “The slave women of ‘Umar used to serve us bare-headed, with their breasts jiggling and their ankles showing.”
Thus the report is proven, but what is known and circulated among scholars is the version narrated by al-Bayhaqi, “with their hair coming down to their breasts.” As for the version which says “with their breasts jiggling,” this comes from the report of Ibn Salam which is referred to above. Its isnad includes Nasr ibn Tarif, who was accused of lying. Yahya said: He is one of those who are known for fabricating hadiths. Al-Fallas said: He is one of those regarding whom there is consensus that they are liars and no report is to be narrated from them; one of them is Abu Jizzi al-Qassab Nasr ibn Tarif.
See: Lisan al-Mizan (6/153).
Based on the above:
The report is sound, but only in the version which says “bare-headed, with their hair coming down to their breasts.” What is meant is that their hair came down to their chests and moved due to their quick movements as they worked hard to serve the guests.
As for the version which says “with their breasts jiggling,” it is not sahih. Even if we were to assume that it is sahih, it is to be interpreted according to the first version, which is that they were old women, not young women with firm breasts, and because they were working hard to serve the guests, that happened to them.
Islamic teachings differentiate between free women and slave women. The free woman is to observe complete hijab, whereas slave women do not have to wear hijab, and it is permissible for a slave woman to uncover her head, hands and face, because of the need to move a great deal as they do their work, and imposing hijab on them would cause them great hardship, in addition to the fact that people do not usually find them attractive.
Ibn Kathir (may Allah have mercy on him) said:
The verse {this will make it more likely that they will be recognized [as chaste women] and will not be harassed} [al-Ahzab 33:59] means: if they do that, they will be known to be free women, not slave women, and not prostitutes.
Mujahid said: They were to wear jilbab (a garment that comes down from the top of the head and covers the entire body), so that it would be known that they were free women, and so that no evildoer would bother them or harass them."(Tafsir Ibn Kathir  6/425-426).
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said:
Hijab is only for free women, not slave women, as was the practice of the believers at the time of the Prophet (blessings and peace of Allah be upon him) and his successors (the caliphs). Free women observed hijab and slave women did not. If ‘Umar (may Allah be pleased with him) saw a slave woman covering her head, he would hit her and say: Are you trying to imitate free women, O foolish one? So slave women would uncover their heads, hands and faces."(Majmu‘ al-Fatawa 15/372).
Hence al-Bayhaqi said, after quoting this report: The reports from ‘Umar ibn al-Khattab (may Allah be pleased with him) regarding that are sahih. This indicates that the slave woman’s head and neck, and what appears of her when she is serving others are not ‘awrah. End quote.
Thirdly:
What has been explained above about the ‘awrah of a slave woman only applies when there is no risk of fitnah (temptation) and people have decency and would not be tempted by her. But if there is the fear of temptation, or there are many dubious and corrupt people, and there is the fear that they could annoy or harass slave women, then in that case slave women must observe hijab, and men must avert their gaze from them and they must avert their gaze too.
Shaykh al-Islam Ibn Taymiyah (may Allah have mercy on him) said:
Similarly, if there is the fear that a slave woman could cause temptation to others, then she must cover herself with a jilbab and observe hijab; men must avert their gaze from her and she must also avert her gaze.
There is nothing in the Qur’an or Sunnah to suggest that it is permissible to look at slave women, or that they should not observe hijab and may show their adornments. But the Qur’an does not give the same instructions to them as to free women. The Sunnah distinguishes between them and free women in practical terms, but there is no statement in the Sunnah to differentiate between them in words. Rather the custom of the believers was that free women would observe hijab, and slave women would not.
The Qur’an makes one exception in the case of free women, namely for elderly women who have no interest in marriage. And in the case of men, an exception is made for male retainers [dependants or followers who are attached to a tribe or family] who are free of physical desire. It is not forbidden to show hidden adornment to them, because they have no desire, so it is more appropriate that some slave women should be exempted from having to cover. This applies to those who would not provoke desire and temptation if they do not observe hijab and they show their adornment.
If a slave woman’s appearing uncovered and people’s looking at her would result in temptation, then that must be prevented, as in the case of other women.
The same applies to men with men, and women with women. If a woman could tempt other women, or if a man could tempt other men, then the command to avert the gaze and not look at them is applicable, as is the command to restrain carnal desires.
Hence if slave women and boys are beautiful and there is the fear that temptation may result from looking at them, the same ruling applies to them, as the scholars have stated."(Majmu‘ al-Fatawa 15/373-377).
He also said:
At the time of the Sahabah, slave women used to walk in the streets bare-headed and they would serve men at a time when people had decency. But now, if a man wants to let these beautiful Turkish slave women walk among the people, in a land such as this and at a time such as this, as the people allowed slave women to walk [in the streets, at the time of the Sahabah], that would lead to a great deal of mischief."(Majmu‘ al-Fatawa 15/418).
See: I‘lam al-Muwaqqi‘in by Ibn al-Qayyim (may Allah have mercy on him) (2/46-47).
For more information, please see the answer to question no. 8489 .
And Allah knows best.