A Commentary, Critical, Practical, and Explanatory on the Old and New Testaments, by Robert Jamieson, A.R. Fausset and David Brown  at sacred-texts.com
jer 41:1ISHMAEL MURDERS GEDALIAH AND OTHERS, THEN FLEES TO THE AMMONITES. JOHANAN PURSUES HIM, RECOVERS THE CAPTIVES, AND PURPOSES TO FLEE TO EGYPT FOR FEAR OF THE CHALDEANS. (Jer. 41:1-18)
seventh month--the second month after the burning of the city (Jer 52:12-13).
and the princes--not the nominative. And the princes came, for the "princes" are not mentioned either in Jer 41:2 or in Kg2 25:25 : but, "Ishmael being of the seed royal and of the princes of the king" [MAURER]. But the ten men were the "princes of the king"; thus MAURER'S objection has no weight: so English Version.
eat bread together--Ishmael murdered Gedaliah, by whom he was hospitably received, in violation of the sacred right of hospitality (Psa 41:9).
jer 41:2slew him whom the king of Babylon had made governor--This assigns a reason for their slaying him, as well as showing the magnitude of their crime (Dan 2:21; Rom 13:1).
jer 41:3slew all the Jews--namely, the attendants and ministers of Gedaliah; or, the military alone, about his person; translate, "even (not 'and,' as English Version) the men of war." The main portion of the people with Gedaliah, including Jeremiah, Ishmael carried away captive (Jer 41:10, Jer 41:16).
jer 41:4no man knew it--that is, outside Mizpah. Before tidings of the murder had gone abroad.
jer 41:5beards shaven, &c.--indicating their deep sorrow at the destruction of the temple and city.
cut themselves--a heathen custom, forbidden (Lev 19:27-28; Deu 14:1). These men were mostly from Samaria, where the ten tribes, previous to their deportation, had fallen into heathen practices.
offerings--unbloody. They do not bring sacrificial victims, but "incense," &c., to testify their piety.
house of . . . Lord--that is, the place where the house of the Lord had stood (Kg2 25:9). The place in which a temple had stood, even when it had been destroyed, was held sacred [PAPINIAN]. Those "from Shiloh" would naturally seek the house of the Lord, since it was at Shiloh it originally was set up (Jos 18:1).
jer 41:6weeping--pretending to weep, as they did, for the ruin of the temple.
Come to Gedaliah--as if he was one of Gedaliah's retinue.
jer 41:7and cast them into . . . pit--He had not killed them in the pit (compare Jer 41:9); these words are therefore rightly supplied in English Version. "The pit" or cistern made by Asa to guard against a want of water when Baasha was about to besiege the city (Kg1 15:22). The trench or fosse round the city [GROTIUS]. Ishmael's motive for the murder seems to have been a suspicion that they were coming to live under Gedaliah.
jer 41:8treasures--It was customary to hide grain in cavities underground in troubled times. "We have treasures," which we will give, if our lives be spared.
slew . . . not-- (Pro 13:8). Ishmael's avarice and needs overcame his cruelty.
jer 41:9because of Gedaliah--rather, "near Gedaliah," namely, those intercepted by Ishmael on their way from Samaria to Jerusalem and killed at Mizpah, where Gedaliah had lived. So Ch2 17:15, "next"; Neh 3:2, Margin, literally, as here, "at his hand." "In the reign of Gedaliah" [CALVIN]. However, English Version gives a good sense: Ishmael's reason for killing them was because of his supposing them to be connected with Gedaliah.
jer 41:10the king's daughters-- (Jer 43:6). Zedekiah's. Ishmael must have got additional followers (whom the hope of gain attracted), besides those who originally set out with him (Jer 41:1), so as to have been able to carry off all the residue of the people. He probably meant to sell them as slaves to the Ammonites (see on Jer 40:14).
jer 41:11Johanan--the friend of Gedaliah who had warned him of Ishmael's treachery, but in vain (Jer 40:8, Jer 40:13).
jer 41:12the . . . waters-- (Sa2 2:13); a large reservoir or lake.
in Gibeon--on the road from Mizpah to Ammon: one of the sacerdotal cities of Benjamin, four miles northwest of Jerusalem, now Eljib.
jer 41:13glad--at the prospect of having a deliverer from their captivity.
jer 41:14cast about--came round.
jer 41:16men of war--"The men of war," stated in Jer 41:3 to have been slain by Ishmael, must refer to the military about Gedaliah's person; "the men of war" here to those not so.
eunuchs--The kings of Judah had adopted the bad practice of having harems and eunuchs from the surrounding heathen kingdoms.
jer 41:17dwelt--for a time, until they were ready for their journey to Egypt (Jer. 42:1-22).
habitation to Chimham--his "caravanserai" close by Beth-lehem. David, in reward for Barzillai's loyalty, took Chimham his son under his patronage, and made over to him his own patrimony in the land of Beth-lehem. It was thence called the habitation of Chimham (Geruth-Chimham), though it reverted to David's heirs in the year of jubilee. "Caravanserais" (a compound Persian word, meaning "the house of a company of travellers") differ from our inns, in that there is no host to supply food, but each traveller must carry with him his own.
jer 41:18afraid--lest the Chaldeans should suspect all the Jews of being implicated in Ishmael's treason, as though the Jews sought to have a prince of the house of David (Jer 41:1). Their better way towards gaining God's favor would have been to have laid the blame on the real culprit, and to have cleared themselves. A tortuous policy is the parent of fear. Righteousness inspires with boldness (Psa 53:5; Pro 28:1).