Abu Wa'il narrates that Sayyiduna Ammar bin Yasir (may Allah be pleased with him) delivered to us a very eloquent and concise sermon. Then when he descended from the pulpit, we said to him, "O Abu Yaqzan, you have delivered a very eloquent and concise sermon; if you had made it longer, it would have been better." He replied, "Indeed, I heard the Messenger of Allah (peace and blessings be upon him) say: 'Verily, the lengthening of a man's prayer and the brevity of his sermon are signs of his understanding (fiqh). Therefore, make the prayer long and the sermon short. For indeed, some speech has the effect of magic.'" Abdul Rahman bin Abdul Malik bin Abjar narrated similarly as above, but did not mention the words: "If you had made the sermon longer, it would have been better."
Imam Abu Bakr, may Allah have mercy on him, says that in the hadith of Sayyiduna Jabir bin Samurah, may Allah be pleased with them both, it is mentioned that the sermon of the Messenger of Allah, peace and blessings be upon him, used to be moderate.
In the narration of Hazrat Hakam bin Huzn from the Noble Prophet (peace be upon him), it is mentioned that the Prophet (peace be upon him) praised Allah Almighty and glorified Allah with pure, concise, and blessed words.