Silsilat al-Ahadith al-Sahihah

A man from the tribe of Banu Amir came to the Prophet Muhammad (peace be upon him) and said: May I come in? The Prophet (peace be upon him) said to his slave girl: This man did not seek permission in a good manner, so go and tell him to say: «السلام عليكم» May I come in? The man himself heard this and, before the slave girl reached him, said: «السلام عليكم» May I come in? The Prophet (peace be upon him) said: “«و عليك», come in.” I went to you and asked: What have you brought? The Prophet (peace be upon him) said: I have brought goodness to you. I have come to you so that you worship Allah, the One, with no partner, and abandon the worship of idols like Lat and Uzza, and perform five prayers in the day and night, and fast in the month of (Ramadan) in the year, and perform Hajj to the House of Allah, and take wealth (zakat) from the rich and distribute it among the poor. Indeed, Allah has taught words full of goodness, and that is also knowledge which only Allah knows: “Indeed, with Allah alone is the knowledge of the Hour, He sends down the rain, and knows what is in the wombs. No soul knows what it will earn tomorrow, nor does anyone know in which land he will die. Remember, Allah is All-Knowing, All-Aware.” (Surah Luqman: 34)