Allah's Messenger (ﷺ) said: "If you see someone buying or selling inside the mosque, say: 'May Allah not make your trading profitable!'" [Reported by an-Nasa'i and at-Tirmidhi and the latter graded it Hasan (good)].
وَعَنْهُ : أَنَّ رَسُولَ اَللَّهِ - صلى الله عليه وسلم -{ إِذَا رَأَيْتُمْ مَنْ يَبِيعُ , أَوْ يَبْتَاعُ فِي اَلْمَسْجِدِ , فَقُولُوا : لَا أَرْبَحَ اَللَّهُ تِجَارَتَكَ } رَوَاهُ النَّسَائِيُّ , وَاَلتِّرْمِذِيُّ وَحَسَّنَهُ . [1]
Allah's Messenger (ﷺ) said: "Neither the prescribed punishment nor retaliations should be executed inside the mosque." [Reported by Ahmad and Abu Dawud through a weak Sanad (chain)].
وَعَنْ حَكِيمِ بْنِ حِزَامٍ قَالَ : قَالَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -{ لَا تُقَامُ اَلْحُدُودُ فِي اَلْمَسَاجِدِ , وَلَا يُسْتَقَادُ فِيهَا } رَوَاهُ أَحْمَدُ , وَأَبُو دَاوُدَ بِسَنَدٍ ضَعِيف ٍ [1]
On the day of al-Khandaq (battle of the Trench), Sa'd was injured and Allah's Messenger (ﷺ) pitched a tent for him in the mosque to visit him from a close distance. [Agreed upon].
وَعَنْ عَائِشَةَ -رَضِيَ اَللَّهُ عَنْهَا- قَالَتْ : { أُصِيبَ سَعْدٌ يَوْمَ اَلْخَنْدَقِ , فَضَرَبَ عَلَيْهِ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -خَيْمَةً فِي اَلْمَسْجِدِ , لِيَعُودَهُ مِنْ قَرِيبٍ } مُتَّفَقٌ عَلَيْهِ . [1]
I saw Allah's Messenger (ﷺ) at the door of my house screening me while I watched some Abyssinians (Ethiopians) who were playing in the mosque... (the narration). [Agreed upon].
وَعَنْهَا قَالَتْ : { رَأَيْتُ رَسُولَ اَللَّهِ - صلى الله عليه وسلم -يَسْتُرُنِي , وَأَنَا أَنْظُرُ إِلَى اَلْحَبَشَةِ يَلْعَبُونَ فِي اَلْمَسْجِدِ . . . } اَلْحَدِيثَ . مُتَّفَقٌ عَلَيْهِ . [1]
Allah's Messenger (ﷺ) said: "Spitting in the mosque is a sin and its expiation is burying it." [Agreed upon].
وَعَنْ أَنَسٍ - رضى الله عنه - قَالَ : قَالَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -{ اَلْبُزَاقُ فِي اَلْمَسْجِدِ خَطِيئَةٌ وَكَفَّارَتُهَا دَفْنُهَا } مُتَّفَقٌ عَلَيْهِ . [1]
Allah's Messenger (ﷺ) said: "The House (Judgement Day) will not come until people boast (to each other) with (the construction and decoration of) mosques. [Reported by al-Khamsah except at-Tirmidhi, and Ibn Khuzaimah graded it Sahih (authentic)].
وَعَنْهُ قَالَ : قَالَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -{ لَا تَقُومُ اَلسَّاعَةُ حَتَّى يَتَبَاهَى اَلنَّاسُ فِي اَلْمَسَاجِدِ } أَخْرَجَهُ اَلْخَمْسَةُ إِلَّا اَلتِّرْمِذِيُّ , وَصَحَّحَهُ اِبْنُ خُزَيْمَة َ [1]
Allah's Messenger (ﷺ) said: "The rewards of my Ummah (followers) were shown to me, even a peck of dust a man takes out of the mosque." [Reported by Abu Dawud and at-Tirmidhi. The latter graded it Gharib (having a single narrator), and Ibn Khuzaimah graded it Sahih (authentic)].
وَعَنْ أَنَسٍ - رضى الله عنه - قَالَ : قَالَ رَسُولُ اَللَّهِ - صلى الله عليه وسلم -{ عُرِضَتْ عَلَيَّ أُجُورُ أُمَّتِي , حَتَّى اَلْقَذَاةُ يُخْرِجُهَا اَلرَّجُلُ مِنْ اَلْمَسْجِدِ } رَوَاهُ أَبُو دَاوُدَ , وَاَلتِّرْمِذِيُّ وَاسْتَغْرَبَهُ , وَصَحَّحَهُ اِبْنُ خُزَيْمَةَ . [1]
The Prophet (ﷺ) said: "When you get up to pray, perform ablution perfectly, then face the Qiblah and say: 'Allahu Akbar' (Allah is the Most Great). Then recite a convenient portion of the Qur'an; then bow and remain calmly in that position for a moment, then rise up and stand erect; then prostrate and remain calmly in that position for a moment, then rise up and sit calmly, then prostrate and remain calmly in that position for a moment; then do that throughout your prayer." [Reported by as-Sab'a and the wording is that of al-Bukhari].
And in the narration of an-Nasa'i and Abu Dawud from the Hadith of Rifa'a bin Rafi':
"The Salat (prayer) of one of you will not be complete until he performs Wudu' (ablution) properly as Allah commanded him, then he says Allahu Akbar and Alhamdu lillah and praises Him."
"I saw Allah's Messenger (ﷺ) when he uttered the Takbir, he placed his hands parallel to his shoulders; and when he bowed down, he rested his hands on his knees, then bent his back. When he raised his head up, he stood erect until the bones of his spine became straight. When he prostrated, he placed his arms such that they were neither spread out nor drawn in, and the tips of his toes were facing the Qiblah; when he sat up, at the end of two Rak'a, he sat on his left foot and put erect the right one; and when he sat up after the last Rak'a he put forward the left foot, put erect the other one and sat on his buttock." [Reported by al-Bukhari].
Whenever Allah's Messenger (ﷺ) stood for Salat (prayer), he used to say: "I have turned my face (as a monotheist) towards Him who created the heavens and the earth and I am not from the polytheists. My prayer and my devotion, my life and my death belong to Allah, the Lord of the universe, Who has no partner. That is what I have been commanded, and I am a Muslim. O Allah, You are the King. There is nothing which deserves to be worshipped but You. You are my Rabb (Lord) and I am Your slave. I have wronged myself, but I acknowledge my sin, so forgive me all my sins, You alone can forgive sins; and guide me to the best qualities, You alone can guide to the best of them: and turn me from evil ones, You alone can turn from evil qualities. I come to serve and please You. All good is in Your Hands and evil does not pertain to You. I seek refuge in You and turn to You, You are the Blessed and the Exalted. I ask Your forgiveness and turn to You in repentance." [Reported by Muslim].
Narrated Abu Hurairah (RA) Allah's Messenger (ﷺ) used to keep silent - between the opening Takbir of the prayer and the recitation of the Qur'an - for a short while. Then, I asked him (about that) and he replied, "I say, 'O Allah! Keep me apart from my sins (faults) as you have kept apart the east and west. O Allah clean me from my sins as a white garment is cleaned from dirt. O Allah wash me of my sins with water, snow and hail." [Agreed upon].
He (ﷺ) used to say, "How perfect You are O Allah, and Praise is for You, Blessed is Your Name and Exalted is Your Majesty and there is nothing which deserves to be worshipped besides You." [Reported by Muslim with a Munqati' (broken) chain. And in the version of ad-Daraqutni, it is Mawsul (unbroken chain), and it is Mawquf (saying of a companion ('Umar)].
He (ﷺ) used to say after the (opening) Takbir (for prayer), "I seek refuge in Allah, the All-Hearing and the All-Knowing from the accursed devil, from his madness or evil suggestion (Hamz), from his puffing up (Nafkh), and from his witchcraft (Nafth)."