Etiquette of sitting and sleeping

It is narrated from Abu Shaybah (may Allah have mercy on him) that the Messenger of Allah (peace and blessings be upon him) said: "When one of you comes to a people or a gathering and they make room for him to sit, he should sit right there, for this is in reality a special honour from Allah, the Mighty and Majestic, by which his Muslim brother has honoured him. But if room is not made for him, he should look for the place in the gathering with the most space and room, and sit there."
Imam al-Harith bin Abi Usamah recorded this hadith in his Musnad, and the narrators in its chain are thiqat (trustworthy), while there are also supporting reports for it in other books of hadith.

It is narrated from Sayyiduna Anas (may Allah be pleased with him) that the Prophet (peace and blessings be upon him) said: "The best gatherings and sitting places are those that are the most spacious and wide."
Imam al-Bazzar (may Allah have mercy on him) said: We do not know of this report from Sayyiduna Anas (may Allah be pleased with him) except through this one route, that is, chain.

It is narrated from Yahya bin Ya'mar that the Messenger of Allah (peace and blessings be upon him) passed by a gathering held on a road, and he (peace and blessings be upon him) said: "Beware of (sitting on) the road, for it is the path of the Fire and of Satan." Then he (peace and blessings be upon him) went on, until the Companions thought that this saying of his (peace and blessings be upon him) was a definite and binding command. Then he (peace and blessings be upon him) came back and said: "Unless you fulfil the right of the road." The Companions said: O Messenger of Allah! What is the right of the road? He (peace and blessings be upon him) said: "Lowering your gaze, guiding the one who has lost his way, and returning the greeting of salam."
One narrator in the chain of this report is unidentified (mubham); however, its text is sound on the basis of supporting evidence from other reliable and sahih (authentic) hadith.

Hisham bin Hassan (may Allah have mercy on him) narrates from Imam Muhammad bin Sirin (may Allah have mercy on him) that he "disliked that a man should sleep on his stomach (face down), and that a woman should sleep lying flat on her back."
This report is mawquf and sahih (authentic).

It is narrated from Sayyiduna Abu Sa'id al-Khudri (may Allah be pleased with him) that he was suffering from pain in his foot. His brother came to him and saw that he was lying down and had placed one foot on top of the other. His brother struck that very painful foot with his hand, which caused him severe pain. He said: "You have hurt me! Did you not know that my foot is in pain?" He replied: "Of course (I knew)." Abu Sa'id (may Allah be pleased with him) asked: "Then what prompted you to do this?" He said: "Have you not heard that the Messenger of Allah (peace and blessings be upon him) forbade us from this (lying with one foot over the other)?"
I (Ibn Hajar) say: The name of this brother of his is Qatadah bin al-Nu'man (may Allah be pleased with him).