What is the ruling on departing after the first sermon concludes but before the two sermons are entirely finished, without a valid Sharia excuse?

Attending both parts of the Friday sermon is obligatory, and it is not permissible to leave during the sermon. The sin becomes graver if leaving leads to missing the Friday prayer. It is permissible to leave if there is a compelling excuse, in which case one should pray Dhuhr instead of Jumu'ah. As for other sermons, such as those for the two Eids, attending them is not obligatory, and it is permissible to leave them.