To cast up mounts and build forts - was the business not of the relieving but of the besieging army. Translate it: when men cast up mounts and build forts to destroy many persons.

Neither shall Pharaoh, with his mighty army and great company,

make for him in the war,.... The king of Egypt, to whom Zedekiah applied for horses and men to help him; though he should come with a great army, and a large multitude of people, yet should be of no use to Zedekiah, nor do any hurt to Nebuchadnezzar, or hinder him from taking Jerusalem:

by casting up mounts, and building forts, to cut off many persons; that is, when Nebuchadnezzar should besiege Jerusalem, and raise mounts, and build fortifications, in order to take the city, and destroy its inhabitants; as he did, Jeremiah 52:4; the Egyptian army should not be able to hinder him going on with the siege, and taking the city; for though the siege was broke up for a time, upon the approach of Pharaoh's army, yet Nebuchadnezzar, having conquered the Egyptians, returned again to the siege of Jerusalem, and took it; see Jeremiah 37:5.

Neither shall Pharaoh with his mighty army and great company make for him in the war, by casting up mounts, and building forts, to cut off many persons:

17. Pharaoh-Pharaoh-hophra (Jer 37:7; 44:30), the successor of Necho (2Ki 23:29).

Neither . make for him-literally, "effect (anything) with him," that is, be of any avail to Zedekiah. Pharaoh did not act in concert with him, for he was himself compelled to retire to Egypt.

by casting up mounts, &c.-So far from Pharaoh doing so for Jerusalem, this was what Nebuchadnezzar did against it (Jer 52:4). Calvin Maurer, &c., refer it to Nebuchadnezzar, "when Nebuchadnezzar shall cast up mounts."

17:11-21 The parable is explained, and the particulars of the history of the Jewish nation at that time may be traced. Zedekiah had been ungrateful to his benefactor, which is a sin against God. In every solemn oath, God is appealed to as a witness of the sincerity of him that swears. Truth is a debt owing to all men. If the professors of the true religion deal treacherously with those of a false religion, their profession makes their sin the worse; and God will the more surely and severely punish it. The Lord will not hold those guiltless who take his name in vain; and no man shall escape the righteous judgment of God who dies under unrepented guilt.