Shulchan Arukh, Yoreh De'ah 387

<b>דין כפיית המטה. ובו ב' סעיפים:</b><br>אבל חייב בכפיית המטה ובשעת שינה ואכילה יושב על מטה כפויה אבל כל היום אינו יושב אפילו על מטה כפויה אלא על גבי קרקע וכן המנחמים אינן רשאים לישב אלא ע"ג קרקע:

A mourner is required to overturn the couch. It was customary in those days for people to sit on couches or beds throughout the year. Hence, the mourner is required to overturn his couch and sit on the ground. Cf. however, M.K. 27a where it is stated that in a case of mourning, on the eve of the Sabbath, from the time of the Minḥa (afternoon) service and onwards, the couches were placed in erect position, but the mourner did not sit down on them until it was dark. This shows that the overturning of the couches or beds was on account of the prohibition against sitting on them (v. ibid., Tosaf. s.v. מן המנחה ולמעלה ). According to the opinion of Bar Kappara, even if the mourner sat or slept on the ground, he had to overturn all the beds or couches in his home save a couch used specifically for vestments ( ibid. 27a). When the time for sleeping or eating [arrives], he may sit [or sleep] on an overturned couch, but during the entire day he may not sit even on an overturned couch save on the ground. So too, the comforters are not permitted to sit save on the ground. to M.K. III; RIBaSh, Resp. s. 69; Toldoth Adam we-Ḥawah II, 266a; Tur a.l.; T.H.; Shaare Simḥah p. 46; B.B. 144a, Tosaf. s.v. אודייני ; Yalkut Shimoni II Sam. s. 149; Sem(H). VI, 2; W.G. a.l. for variant readings not found in cur. edd. of Talmud.

עכשיו לא נהגו בכפיית המטה מפני שיאמרו העובדי כוכבים שהוא מכשפות ועוד שאין המטות שלנו עשויות כמטות שלהן כדי שיהא ניכר בהם כפיה:

Now it is not the common practice to overturn the couch because the Gentiles will say that it is [a kind] of sorcery. Moreover, our couches are not made like their couches in order that overturning should be discernible [as it was in former days]. on the authority of Asheri. M.K. 21a, Tosaf. s.v. אלו The mourners may sit on low stools ( contra Ta Z and ShaK ). Support for this may be found in Y.Ber. III, 1(6a); Y.M.K. III, 5(83a), where the reason for overturning the couches is derived from Job. II, 13, ‘So they sat down with him upon the ground seven days’ (v. supra par. 1, n. 1). The text for the words ‘upon the ground’ reads לארץ (lit. ‘(close) to the ground’ ) whence it is inferred that a mourner may sit on a low stool. One who is feeble in health or a pregnant woman may sit on ordinary stools or chairs. On the eve of the Sabbath, a few hours before nightfall, the mourner may rise from the low stools and close to the time of kindling the Sabbath lights, he may put his shoes on — A.H.