What is the recommended length of the sermon on Friday?

Primary text

The sermon should be shortened. The Prophet, peace be upon him, stated that the length of a man's prayer and the shortness of his sermon are indicators of his understanding (*fiqh*). He commanded, 'Lengthen the prayer and shorten the sermon.' Furthermore, his prayers and sermons were described as moderate (*qasd*), and he was known not to prolong his admonition on Friday, keeping it to easy, brief words.