Hadithcore
Sahih al-Bukhari, 95
sahih

Narrated Anas:

Whenever the Prophet (ﷺ) spoke a sentence (said a thing), he used to repeat it thrice so that the people could understand it properly from him and whenever he asked permission to enter, (he knocked the door) thrice with greeting.

حَدَّثَنَا عَبْدَةُ بْنُ عَبْدِ اللَّهِ، حَدَّثَنَا عَبْدُ الصَّمَدِ، قَالَ حَدَّثَنَا عَبْدُ اللَّهِ بْنُ الْمُثَنَّى، قَالَ حَدَّثَنَا ثُمَامَةُ بْنُ عَبْدِ اللَّهِ، عَنْ أَنَسٍ، عَنِ النَّبِيِّ صلى الله عليه وسلم أَنَّهُ كَانَ إِذَا تَكَلَّمَ بِكَلِمَةٍ أَعَادَهَا ثَلاَثًا حَتَّى تُفْهَمَ عَنْهُ، وَإِذَا أَتَى عَلَى قَوْمٍ فَسَلَّمَ عَلَيْهِمْ سَلَّمَ عَلَيْهِمْ ثَلاَثًا‏.‏

References2 variants
In-Book Reference
Book 3, Hadith 37
USC-MSA web (English) reference
Vol. 1, Book 3, Hadith 95 (deprecated numbering scheme)
Sharh · explanationclick to expand
The Prophet (blessings and peace of Allah be upon him) was as Allah described him: {There has certainly come to you a Messenger from among yourselves. Grievous to him is what you suffer; [he is] concerned over you and to the believers is kind and merciful} [at-Tawbah 9:128]. One example of that is his keenness to teach them and make sure they understood the matters of their religion. In this hadith, Anas (may Allah be pleased with him) narrates that the Prophet (blessings and peace of Allah be upon him) used to repeat his words three times when he wanted to exhort them, so that those who were present would understand it and comprehend its meaning, because repetition was most effective in helping people to remember and making the pronunciation clear, so that there would be no room for misinterpretation, especially if there was the fear that his words might not be understood or heard, or if he wanted to convey the message when he was teaching, rebuking or exhorting. This is one of the basic principles of teaching in Islam, because repeating something three times is sufficient to make the meaning clear and leave no excuse for anybody. When the Prophet (blessings and peace of Allah be upon him) came to people, he would greet them with salaam three times, and perhaps this refers to his practice when greeting a large number of people who would not all hear a greeting given once, or it was his practice to make sure that they heard the second and third greeting if he thought that the first one had not been heard, or he would repeat the salaam because he wanted to seek permission to enter, if the first salaam was not heard or responded to. But if he passed by a gathering and greeted everyone present, or he came to a house and gave the greeting of salaam and they responded, then there was no point in repeating it. It may be that when he came to some people, he would give the greeting of salaam by way of seeking permission to enter, then when he entered the house, he would greet them with salaam, then when he got up to leave the gathering he would say salaam to bid farewell, which is like a supplication (dua). .
Related hadiths3
Compare isnād across 3 related chains →