ENOfficial
‘Ammar told how he heard God’s Messenger say, “The length of a man’s prayer and the shortness of his sermon are a sign of his understanding, so make the prayer long and the sermon short, for there is magic in eloquence.” Muslim transmitted it.
Source: sunnah.com
Other translations
Arabic
وَعَنْ عَمَّارٍ قَالَ: سَمِعْتُ رَسُولَ اللَّهِ صَلَّى اللَّهُ عَلَيْهِ وَسَلَّمَ يَقُولُ: «إِنَّ طُولَ صَلَاةِ الرَّجُلِ وَقِصَرَ خُطْبَتِهِ مَئِنَّةٌ مِنْ فِقْهِهِ فَأَطِيلُوا الصَّلَاة واقصروا الْخطْبَة وَإِن من الْبَيَان سحرًا» . رَوَاهُ مُسلم
sunnah.com