Adam Clarke Bible Commentary
Therefore shalt thou fall in the day - In the most open and public manner, without snare or ambush.
And the prophet also shall fall - in the night - The false prophet, when employed in taking prognostications from stars, meteors, etc.
And I will destroy thy mother - The metropolis or mother city. Jerusalem or Samaria is meant.
Carl Friedrich Keil and Franz Delitzsch Old Testament Commentary
"And so wilt thou stumble by day, and the prophet with thee will also stumble by night, and I will destroy thy mother." Kshal is not used here with reference to the sin, as Simson supposes, but for the punishment, and signifies to fall, in the sense of to perish, as in Hos 14:2; Isa 31:3, etc. היּום is not to-day, or in the day when the punishment shall fall, but "by day," interdiu, on account of the antithesis לילה, as in Neh 4:16. נביא, used without an article in the most indefinite generality, refers to false prophets - not of Baal, however, but of Jehovah as worshipped under the image of a calf - who practised prophesying as a trade, and judging from Kg1 22:6, were very numerous in the kingdom of Israel. The declaration that the people should fall by day and the prophets by night, does not warrant our interpreting the day and night allegorically, the former as the time when the way of right is visible, and the latter as the time when the way is hidden or obscured; but according to the parallelism of the clauses, it is to be understood as signifying that the people and the prophets would fall at all times, by night and by day. "There would be no time free from the slaughter, either of individuals in the nation at large, or of false prophets" (Rosenmller). In the second half of the verse, the destruction of the whole nation and kingdom is announced ('ēm is the whole nation, as in Hos 2:2; Heb 4:1).
Jamieson-Fausset-Brown Bible Commentary
fall in the day--in broad daylight, a time when an attack would not be expected (see on Jer 6:4-5; Jer 15:8).
in . . . night--No time, night or day, shall be free from the slaughter of individuals of the people, as well as of the false prophets.
thy mother--the Israelitish state, of which the citizens are the children (Hos 2:2).
John Gill Bible Commentary
Therefore shall thou fall in the day,.... Either, O ye people, everyone of you, being so refractory and incorrigible; or, O thou priest, being as bad as the people; for both, on account of their sins, should fall from their present prosperity and happiness into great evils and calamities; particularly into the hands of their enemies, and be carried captive into another land: and this should be "in the day", or "today" (r); immediately, quickly, in a very short time; or in the daytime, openly, publicly, in the sight of all, of all the nations round about, who shall rejoice at it; or in the day of prosperity, while things go well, amidst great plenty of all good things, and when such a fall was least expected:
and the prophet also shall fall with thee in the night: or the false prophets that are with you, as the Targum, and so Jarchi; either with you, O people, that dwell with you, teach you, and cause you to err; or with thee, O priest, being of the same family, as the prophets, many of them, were priests; now these should fall likewise into the same calamities, as it was but just they should, being the occasion of them: and this should be in the night; in the night of adversity and affliction, in the common calamity; or in the night of darkness, when they could not see at what they stumbled and fell, and so the more uncomfortable to them; or as the one falls in the day, the other falls in the night; as certainly as the one falls, so shall the other, and that very quickly, immediately, as the night follows the day:
and I will destroy thy mother; either Samaria, the metropolis of the nation; or the whole body of the people, the congregation, as the Targum, and Kimchi, and Ben Melech, being as a mother with respect to individuals; and are threatened with destruction because the corruption was general among prophets, priests, and people, and therefore none could hope to escape.
(r) "hodie", Munster, Montanus, Drusius, Tarnovius, Rivet; "hoc tempore", Pagninus. So Kimchi and Ben Melech.