Muslim relates this report.

It constitutes proof that reciting a surah—or part of one—during the Friday sermon is legislated. The Prophet’s, peace and blessings be upon him, constant choice of this surah shows his deliberate preference for what is most effective in admonition and reminder, and it indicates that reiterating exhortation within the sermon is permissible.

Miscellaneous rulings
12 – If a need arose, or a questioner sought his guidance, he would break off his sermon, attend to the matter, answer the questioner, and then complete the sermon.
When he noticed a poor person or someone in need among the congregation, he commanded the people to give charity and encouraged them to do so.
Whenever he mentioned Allah the Exalted, he gestured with his index finger.

I say: It is as though he were alluding to the hadith of ʿImārah ibn Ruwaybah, who saw Bishr ibn Marwān on the pulpit raising his hands and remarked, “May Allah disfigure these two hands! I saw the Messenger of Allah, peace and blessings be upon him, do no more than this,” and he pointed with his forefinger.