WE RELATE FROM the book of Ibn as-Sunnī that ‘Ā’ishah 
reported that the Messenger of Allah 
said: “Digest your food with dhikr of Allah and with ṣalāh; and do not sleep on it lest your hearts become hard.” [1].
reported that the Messenger of Allah said: “Digest your food with dhikr of Allah and with ṣalāh; and do not sleep on it lest your hearts become hard.” [1].Allah 
says: “Then when you enter houses, greet each other—a greeting from Allah of blessing and goodness.” [2].
says: “Then when you enter houses, greet each other—a greeting from Allah of blessing and goodness.” [2].
Allah says: “When a greeting is offered to you, respond with a better greeting, or return the same.” [3].
says: “When a greeting is offered to you, respond with a better greeting, or return the same.” [3].
Allah says: “Do not enter houses other than your own, until you have asked permission and greeted those in them.” [4].
says: “Do not enter houses other than your own, until you have asked permission and greeted those in them.” [4].
Allah says: “And when the children among you come of age, let them [also] ask for permission, as did those before them.” [5].
says: “And when the children among you come of age, let them [also] ask for permission, as did those before them.” [5].
Allah says: “Has the story reached you of the honoured guests of Ibrāhīm? They entered his presence, and said: ‘Peace!’ He replied, ‘Peace!’” [6].
says: “Has the story reached you of the honoured guests of Ibrāhīm? They entered his presence, and said: ‘Peace!’ He replied, ‘Peace!’” [6].
Know that the essence of greeting is established by the Book, the Sunnah, and the consensus of the Ummah. The specific and subsidiary rulings, however, are innumerable. I will summarise the essence of it in brief chapters, if Allah wills. All ability, guidance, rectitude and care are granted by Him.
wills. All ability, guidance, rectitude and care are granted by Him.References
[1] Ibn as-Sunnī (489) and al-Futūḥāt (5/264). According to Ibn Ḥajar, this is not an established hadith, even though its meaning is strong.
[2] Qur’ān 24:61.
[3] Qur’ān 4:86.
[4] Qur’ān 24:27.
[5] Qur’ān 24:59.
[6] Qur’ān 51:24.