بُلُوغُ الْمَرَامِ
Bulugh al-Maram 452
The Book of Prayer
وَعَنْ عَمَّارِ بْنِ يَاسِرٍ رَضِيَ اَللَّهُ عَنْهُمَا قَالَ: سَمِعْتُ رَسُولَ اَللَّهِ - صلى الله عليه وسلم -يَقُولُ: { إِنَّ طُولَ صَلَاةِ اَلرَّجُلِ, وَقِصَرَ خُطْبَتِهِ مَئِنَّةٌ مِنْ فِقْهِهِ } رَوَاهُ مُسْلِمٌ . [1] .
Narrated 'Ammar bin Yasir (RA): He heard Allah's Messenger (ﷺ) say: "The length of a man's prayer and the shortness of his Khutbah (religious talk) are a sign of his understanding (of the religion)." [Reported by Muslim].
Sunnah.com reference: Book 2, Hadith 372