The masjid is the house of Allahﷻ. And so, it has etiquette that must be followed as is the case in any august and holy place.
Abu Hurairah (R) said that Rasoolullahﷺ said, “Whoever purifies himself in his house then walks to one of the houses of Allahﷻ in order to perform one of the duties enjoined by Allahﷻ for every two steps he takes, one will erase a sin and the other will raise him one degree in status.” [Muslim]
Buraydah al-Aslami (R) said that Rasoolullahﷺ said, “Give glad tidings to those who walk to the mosque in darkness, of perfect light on the Day of Resurrection.” [Abu Dawood]
Do not run to catch the Rak’a but walk in a dignified manner.
Abu Huraira (R) reported that Rasoolullahﷺ said, “When the prayer is established, do not come to it running, but rather come to it walking. You must be calm, for if you reach it in time, you may pray it. If you miss anything of it, you may complete it.” In another narration, Rasoolullahﷺ said, “Verily, when you are deliberately walking to prayer, you are in a state of prayer.” [Bukhari & Muslim]
If the Jama’a Salah has not begun, one must pray 2 Raka’at Nafl Salah as Tahiyyatul Masjid before they sit down. Then they must sit and make Dhikr, read Qur’an or remain silent and wait for the Jama’a to start.
Abu Qatadah (R) reported, “Rasoolullahﷺ said, “When one of you enters the masjid, let him pray two Raka’at before he sits down.” [Bukhari & Muslim].
While praying behind the Imam, one must make Takbir with the Imam, fold hands, right hand over left wrist, across the middle of the body, above the navel and remain silent and listen attentively to the recitation. Those who pray with their arms by their sides must do that. Allahﷻ said:
وَإِذَا قُرِئَ ٱلْقُرْءَانُ فَٱسْتَمِعُوا۟ لَهُۥ وَأَنصِتُوا۟ لَعَلَّكُمْ تُرْحَمُونَ
A’araf 7: 204 So, when the Quran is recited, listen to it and be silent that you may receive mercy.
Holding a Mus’haf or device in your hand and reading from it, is against this order of Allahﷻ, because instead of listening attentively, you are reading and so, it is prohibited. Also, if you are holding the Mus’haf or device, you can no longer fold your hands of have them by your sides, so it negates your Salah. Anyone who does so, has left Salah.
Rasoolullahﷺ said, “The imam has been appointed to be followed, so when he says Takbir, then say Takbir, and when he recites, then listen attentively.”
When you are praying alone, say Tahajjud, and want to read from the Mus’haf you may do so, since you are not following an Imam who is reciting. You can keep a stand or table to rest the Mus’haf when you go into Ruku and Sujood. Please do not place the Mus’haf on the floor or your prayer mat.
An Imam, who is not a Hafiz, is also permitted to read from the Mus’haf to lead Nafl Salah like Taraweeh. But anyone following an Imam is not permitted to read from the Mus’haf or device while in Salah. While in Salah one should never be or look like a person who an onlooker might think is not in salat. Postural hijab should always be maintained so that the other person will avoid communicating with the praying person.
Allahﷻ said about our clothing and appearance:
يَـٰبَنِىٓ ءَادَمَ خُذُوا۟ زِينَتَكُمْ عِندَ كُلِّ مَسْجِدٍ وَكُلُوا۟ وَٱشْرَبُوا۟ وَلَا تُسْرِفُوٓا۟ إِنَّهُۥ لَا يُحِبُّ ٱلْمُسْرِفِينَ
A’araf 7: 21 O Children of Adam! Take your adornment to all masjids (wear clean clothes that cover the body) and eat and drink but waste not by extravagance, certainly He (Allah) likes not Al-Musrifun (the extravagant).
We must ensure that we are free from all offensive odors. Rasoolullahﷺ prohibited those who had eaten onions or garlic to come to the masjid. Narrated Jabir bin ‘Abdullah, “Rasoolullahﷺ said, “Whoever has eaten garlic or onion should keep away from us (or should keep away from our mosque).’
Please ensure that clothing is clean, free from unpleasant smells and loose and not transparent and long enough to cover the Satar (area of the body that is obligatory to cover). For the male this is from above the navel to below the knee. For the woman it is the whole body including the head and hair, except the face and hands. At no point in the Salah must this area (for men and women) become uncovered. If that happens, it breaks the Salah, whether anyone saw it or not. It is our responsibility to wear clothing where when we bend in Ruku and Sujood or sit in Tashahhud our Satar is never exposed.
There are two parts in Salah. A part where the Iman recites aloud as in the recitation of Qur’an in Fajr, Maghrib and Isha and in the pronouncing of the Takbiraat and Tasleem. The rest of the Salah is silent and what is read must be read silently. For those following the Imam, the whole Salah is silent. It is permissible to move your lips and to recite Sura Al-Fatiha and say the Takbiraat and Tasbihaat in Ruku and Sujood and Tashahhud in a tone that only you can hear. It is not permissible to do this either in a stage whisper that carries across the room or to do it audibly.
Narrated Abu Sai’d Al Khudri (R) that Rasoolullahﷺ said, “Every one of you is calling his Rabb quietly. One should not trouble the other and one should not raise his voice in recitation or prayer over the voice of the other.”
Finally, when you finish praying, leave quietly. Do not stand around and speak to other people because that disturbs those who are praying.
Please bring your children to the masjid because being in the masjid environment is good for them. But ensure that they are always with you and not running wild. Let their visit to the masjid be a time of Tarbiyya for them and an opportunity to spend quality time with their parents. Let not your children become a source of disturbance and irritation for other worshippers. Just as you ensure that they behave well, remain silent and attentive in a library or museum, do it in the masjid because the house of Allahﷻ deserves it more. May Allahﷻ enable us to benefit from being in His houses as His guests and receive His Mercy and Forgiveness.