عَنْ أَنَسٍ رَضِيَ اللَّهُ عَنْهُ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَآلِهِ وَسَلَّمَ كَانَ إِذَا تَكَلَّمَ بِكَلِمَةٍ رَدَّدَهَا ثَلَاثًا وَإِذَا أَتَى قَوْمًا فَسَلَّمَ عَلَيْهِمْ ثَلَاثًا
It is narrated from Sayyiduna Anas that when the Messenger of Allah, peace and blessings be upon him, spoke, he would repeat his words three times, and similarly, when he greeted people with salam, he would say salam to them three times.