[Al-Bukhari].

Messenger of Allah (ﷺ) directed me thus: "Whenever you go to bed, perform Wudu' as you do for Salat then (before sleeping) recite: 'O Allah! I have submitted myself to You, I have turned myself to You, committed my affairs to You and sought Your refuge for protection out of desire for You and fear of You (expecting Your reward and fearing Your punishment). There is no refuge and no place of safety from You but with You. I believe in the Book You have revealed and in the Prophet (ﷺ) You have sent."' Messenger of Allah (ﷺ) added: "If anyone recites these words and dies during the night, he will die on the true Deen, and if he remains alive till the morning, he will obtain good. And make this supplication your last words (before sleeping)."[Al-Bukhari and Muslim].

The Prophet (ﷺ) used to offer eleven Rak'ah of optional Salat (prayers) in the latter part of night. When it was about dawn, he would offer two short Rak'ah and then would lie down on his right side till the Mu'adhdhin (one who calls for prayer) would come to inform him that the congregation had gathered (for prayer).[Al-Bukhari and Muslim].

Whenever the Prophet (ﷺ) lay down for sleep at night, he would place his (right) hand under his (right) cheek and supplicate: "Allahumma bismika amutu wa ahya [O Allah, with Your Name will I die and live (wake up)]." And when he woke up, he would supplicate: "Al-hamdu lillahil-ladhi ahyana ba'da ma amatana, wa ilaihin-nushur (All praise is due to Allah, Who has brought us back to life after He has caused us to die, and to Him is the return)."[Al-Bukhari].

My father said: I was lying down on my belly in the mosque when someone shook me with his foot and said, "Lying down this way is disapproved by Allah." I looked up and saw that it was Messenger of Allah (ﷺ).[Abu Dawud].

Messenger of Allah (ﷺ) said, "Whoever sits in a place where he does not remember Allah (SWT), he will suffer loss and incur displeasure of Allah; and whoever lies down (to sleep) in a place where he does not remember Allah, he will suffer sorrow and incur displeasure of Allah."[Abu Dawud].

[Al-Bukhari and Muslim].

After the Fajr (dawn) prayer the Prophet (ﷺ) used to sit crossed legged in the same place in which he had prayed till the sun shone brightly.[Abu Dawud].

I saw Messenger of Allah (ﷺ) sitting in the compound of the Holy Ka'bah, with the thighs against the stomach and arms around his legs.[Al- Bukhari].

I saw the Prophet (ﷺ) seated with his arms enfolding his legs; and when I saw him in such a state of humble guise I trembled with fear due to the awe (he showed in that posture).[Abu Dawud and At-Tirmidhi].

Messenger of Allah (ﷺ) passed by me when I was sitting with my left hand behind my back and leaning on my palm. On seeing me in this posture he said, "Do you sit like those upon whom the Wrath of Allah has descended?"[Abu Dawud].

[Al-Bukhari and Muslim].

Messenger of Allah (ﷺ) said, "If someone leaves his seat (for one reason or another) and returns to it, he is better entitled to it."[Muslim].

Whenever we came to the gathering of the Prophet, we would sit down at the end (of the assembly).[Abu Dawud and At-Tirmidhi].

Messenger of Allah (ﷺ) said, "If a man takes a bath on Friday, purifies himself thoroughly, uses oil and perfume which is available in the house, sets forth for the mosque, does not (forcibly) sit between two persons, offers the prayer that is prescribed for him and listens to the Imam silently, his sins between this Friday and the previous Friday will be forgiven."[Al- Bukhari].

And in a version narrated by Abu Dawud "He should not sit between two men without their permission."

A man sat in the middle of a circle so Hudhaifah (May Allah be pleased with him) said: Cursed upon the tongue of Muhammad (ﷺ) or [he said] Allah has cursed upon the tongue of Muhammad (ﷺ) he who sits in the middle of the circle [of a gathering].

[At-Tirmidhi].

I heard Messenger of Allah (ﷺ) saying "The best assemblies are those in which people make room for one another."[Abu Dawud].

Messenger of Allah (ﷺ) said, "Whoever sits in a gathering and indulges in useless talk and before getting up supplicates: 'Subhanaka Allahumma wa bihamdika, ash-hadu an la ilaha illa Anta, astaghfiruka wa atubu ilaika (O Allah, You are free from every imperfection; praise be to You. I testify that there is no true god except You; I ask Your Pardon and turn to You in repentance),' he will be forgiven for (the sins he may have intentionally or unintentionally committed) in that assembly."[At-Tirmidhi].