The blessed Verse 41 is saying that Divinely appointed...
The blessed Verse 41 is saying that Divinely appointed warners came unto them one after the other. The people of Pharaoh does not only include his family and kith and kin but it encompasses all his followers as well, since although the Arabic word al is often used in the sense of family but it may also be employed in a general sense. The contextual meaning of the blessed Verse in question makes a reference to the latter sense.
The Arabic word nudhur is the plural form of nadhir denoting "warner." Nadhir may be either a human being or an incident warning mankind against the consequences of their deeds. The former sense may herein allude to Moses (as) and Aaron and the latter one may make a reference to the nine miracles worked by Prophet Moses (as). However, the following blessed Verse reflects that the latter sense is being intended.
The blessed Verse 42 exposes the reaction of the people of Pharaoh against the two eminent Prophets (as) and their warnings saying that the people of Pharaoh denied Divine Signs. These arrogant wrong-doers belied all Divine Signs unexceptionally and regarded all of them as lies, magic, or coincidence. The blessed Verses in question encompass a wide range of meanings including intellectual and narrational arguments and miracles.
However, taking into account another blessed Verse ^1 according to which God Almighty provided Moses (as) with nine crystal clear miracles, it becomes evident that these miracles are being intended herein. Witnessing only one of these miracles with prior notice and then removal of the affliction through the Prophet's (as) invocation will suffice to convince the truth seeking man. But if one happens to be obdurate, all the miracles of the earth and the heaven may not suffice to convince him.
It is at such time that only Divine Torment should be inflicted upon disobedient people and shatters their brains. As it is mentioned in the blessed Verse in question; "We seized them and chastised them" and the seizure is done by One who may not be vanquished since He is All-Mighty and Omnipotent. The expression mentioned in this account in unprecedented in others since the people of Pharaoh were above all proud of their might and rank and their sovereignty was well-known.
However, God Almighty is saying that He seized them by His Might so that it may be known to all that such groundless might and grandeur is nothing against Divine Omnipotence and Glory.