Abu Waail reported,

Ammar delivered a sermon to us that was brief yet profoundly eloquent. When he descended from the pulpit, we said to him, "Abu al-Yaqzan, you spoke with great eloquence and brevity. If only you had spoken at greater length!"He replied, "I heard the Messenger of Allah ﷺ say, 'A man's lengthy prayer and short sermon are a sign of his understanding. So lengthen the prayer and shorten the sermon, for indeed some eloquent speech is like magic.'"

Azami 3311

Sahih

عن أبي وائل قال

خطبنا عمار فأوجز وأبلغ، فلما نزل قلنا: يا أبا اليقظان! لقد أبلغت وأوجزت، فلو كنت تنفست! فقال: إني سمعت رسول الله ﷺ يقول: إن طول صلاة الرجل وقصر خطبته مئنة من فقهه. فأطيلوا الصلاة، وأقصروا الخطبة، وإن من البيان لسحرا.

الأعظمي 3311صحيح
Contents
Reference
Commentary
Ayat
Collection
Jami al-Kamil
Book
Friday
Chapter
Friday sermon
Section
Recommendation of long prayer and short sermon
Numbering
Jami al-Kamil 3311 (2nd edition)