1. Baraa Radiyallahu 'Anhu reports: "When Rasulullah Sallallahu 'Alayhi Wasallam retired, he put his right hand under his right cheek, and recited this du'aa: Rabbi qini adhaa-baka yauma tub-a-thu 'ibaadaka.
O Allah, save me from Your punishment on the day of qiyaamah".
It is stated in the Hisn Haseen that Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam recited this du'aa thrice. This has also been reported by 'Abdullah bin Mas'ud Radiyallahu 'Anhu in a narration. We find that this was the general Practice of Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam, which many Sahaabah Radiyallahu 'Anhum had witnessed. Although Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam was sinless, he recited these types of du'aas (supplications) to express his humbleness and bond-manship. It is proper that a devoted worshipper asks only his creator, or this was done to educate the ummah. It is clear, from this hadith that Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam slept on his right side. This was his noble practice. Therefore it is mustahab to sleep on the right side. A special benefit may be derived from this. The heart is on the left side of the chest, and by sleeping on the right side, the heart remains on the top side. One will not have a deep sleep, but will sleep lightly. If one sleeps on the left side, the heart will be at the bottom, which will result in a deep slumber. Some physicians have for this reason said, that it is good to sleep on the left side, because if one has a deep sleep, the food digest better. This is a fact. But there is a harm too, which has not be taken into consideration. If the heart is at the bottom, the weight of the whole body will be on it and this will affect it. The heart is one of the main organs of the body. Putting a little pressure on it may cause many diseases. Therefore, medically speaking, if it is good to sleep on the left, then too it is detrimental, from which one should at all times take precaution. In this respect, from the medical point of view it is important to sleep on the right side. Besides, sleeping on the right side reminds one of the grave. We have been commanded to remember death regularly. Many worldly and religious benefits are derived by constantly remembering death. One should constantly remember the breaker of all pleasures. The fact is this, how can one forget a thing that every being will experience which is sure to come and it is not known when it shall take place?
2. Hudhayfah Radiyallahu 'Anhu says: "When Rasulullah Sallallahu 'Alayhi Wasallam lay down on a bed, he recited: Allahurmma bi-ith-mika a-mutu wa ahyaa.
O Allah! In Thy name do I live and die".
When he awakened he recited this du'aa: Alhamdulillaahil ladhi ahyaanaa ba'da rnaa amaatana wa-ilayhin nushur.
'Praise be to Allah Who restored unto us life, having caused us to die and unto Him shall be the Resurrection"'.
Sleep is synonymous with death. That is why sleep has been linked to death, and waking with life. For this reason too one should sleep on the right side, as sleeping is an example of death. Because sleep is likened to death, and waking up is becoming alive again. The 'ulama have written, it is a thing that should be pondered upon, that, after dying in this manner on the day of qiyaamah one will be given life again. In reality Allah 'Ta'aala has made this world a little replica of the hereafter. An example of everything has been made in this world so that one may ponder and take heed of things to come. The life in this world is not more than a dream. A person is happy, affluent, possessing all types of luxuries and does not experience any sort of trouble. If this person sees in a dream that he is being taken to jail and flogged, and is experiencing all types of calamities, not realising that it is a dream, he is distressed, and crying too. Suddenly the eyes open and all the tranquillity and happiness returns. The troubles of this dream does not remain nor are its effects felt. In the same manner, this is the state of a pious person. All the difficulties that are experienced in this world, are like a dream. After opening the eyes when all the happiness is experienced, what effect shall the dream have? But imagine the opposite? If one is experiencing luxuries in a dream, then on awakening one finds oneself in jail with all its punishments, what taste shall remain of a sweet dream? If a detainee that is sentenced to hard labour, sees in a dream that he has become king of the worlds, but after awakening finds himself chained in the dark dungeons, of what benefit will this king-manship be to him? The Sahaabah Radiyallahu 'Anhum understood this, they pleasantly endured all hardships, remembering that this life is but like a dream. May the Almighty Allah through His Infinite Mercy also grant us this valuable treasure. His Mercy is widespread.
3. 'Aayeshah Radiyallahu 'Anha narrates: "Every night before Rasulullah Sallallahu 'Alayhi Wasallam slept on his bed, he put together his hands (as in the du'aa) and blew on it and recited (the surahs of) AI-Ikhlaas (Qul huwauahu ahad), AI-Falaq (Qul a'udhu birabbil falaq), and An-Naas (Qui a'udhu birabbin naas) and wiped those parts of the body that he could (wherever the hand could reach). He began with the head, then the face and then the front part of his body. This was done thrice".
The ahaadith state that Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam recited different du'aas before he went to bed. He also recited different surahs and aayaat of the Qur-aan. It is reported from Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam that if one recites a portion of the Qur-aan before sleeping, an angel is appointed to protect one till one awakens. From the above hadith it is found that Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam himself recited the three surahs mentioned. Besides these, it has been narrated that he recited the musabbihaat. i.e. those surahs that begin with Sabbaha, Yusabbibu, Subhaana etc. He also regularly recited the Surahs of (Alif Laam) Sajdah and Surah Mulk (Tabaarak). The ahaadith state that he also recited the Aayatul Kursi and the last two aayahs of Suratul Baqarah. A sahabi reports that, Sayidina Rasulullah Sallallahu 'Alayhi Wasallam Advised him to recite Suratul Kaafirun (Qul yaa ayyuhal kaafirun) before retiring to bed. Besides these, other du'aas have been narrated that were read by Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam before sleeping. - Fathul Baari.
4. Ibn 'Abbaas Radiyallahu 'Anhu reports: "Once Rasulullah Sallallahu 'Alayhi Wasallam slept and began snoring. It was, the nature of Rasulullah Sallallahu 'Alayhi Wasallam that he snored, when he slept. Bilaal Radiyallahu 'Anhu gave the call to prepare for salaah. Rasulullah Sallallahu 'Alayhi Wasallam awakened and performed the salaah. He did not perform the wudu". This hadith has a detailed incident.
It is a peculiarity of the Ambiyaa that their wudu does not become invalid by sleeping. For this reason Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam did not perform wudu. Sayyidina Rasulullah Sallallahu 'Alayhi Wasallam informed us of the reason. When the Ambiyaa sleep their hearts and minds do not sleep, only their eyes sleep. The dreams of the Ambiyaa are also revelations. They are protected from the influence of the shaytaan. The incident that Imaam Tirmidhi refers to took place at the House of the aunt of Sayyidina ibn 'Abbaas Radiyallahu 'Anhu.
5. Anas bin Maalik Radiyallahu'Anhu says: "When Rasulullah Sallallahu 'Alayhi Wasallam went to bed, he recited this du'aa:
Alhamdulillaahil ladhi at'a-manaa wa-saqaanaa wa-kafaanaa wa-aa-waa-naa-fa-kam mim-mal laa kaafiya lahu wa-laa mu-wiya.
'Praise be to Allah Who gave us food and drink, provided us sufficiently, and gave us (a place for) shelter! How many there are who have neither a provider nor a shelterer!'"
6. Abu Qataadah Radiyallahu 'Anhu relates: "If Rasulullah Sallallahu 'Alayhi Wasallam made an early journey-break in the last portion of the night on his travels, he slept on his right side. If he was staying there till before the morning, he lifted his right arm, put his head on it and slept".
The reason being that if there was more time he lay flat and slept. His noble habit was to sleep on the right side. But if time was short, he lifted his arm and slept on it for a little while. In such circumstances he did not lie flat and sleep, as this might result in a deep slumber, and the time for the salaah would pass.