ENOfficial
Anas told that when God's messenger shook hands with a man, he did not withdraw his hand till the other did so, he did not turn his face away till the other did so, and he was not seen to put forward his knees in front of one with whom he was sitting. Tirmidhi transmitted it.
Source: sunnah.com
Other translations
Arabic
وَعَنْ أَنَسٍ أَنَّ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ كَانَ إِذَا صَافَحَ الرَّجُلَ لَمْ يَنْزِعْ يَدَهُ مِنْ يَدِهِ حَتَّى يَكُونَ هُوَ الَّذِي يَنْزِعُ يَدَهُ وَلَا يَصْرِفُ وَجْهَهُ عَنْ وَجْهِهِ حَتَّى يَكُونَ هُوَ الَّذِي يَصْرِفُ وَجْهَهُ عَن وَجهه وَلم يُرَ مقدِّماً رُكْبَتَيْهِ بَين يَدي جليس لَهُ. رَوَاهُ التِّرْمِذِيّ
sunnah.com