A. Nouns.
Mishmereth (מִשְׁמֶרֶת, Strong's #4931); Mishmâr (מִשְׁמָר, Strong's #4929), “watch; guard; post; confinement; prison; custody; division.” The first or feminine form of this word appears 78 times, while the masculine form is attested 22 times. These forms are scattered through biblical literature.
The noun mishmâr means a “military watch” over a city: “Nevertheless we made our prayer unto our God, and set a watch against them day and night because of them [our enemies]” (Neh. 4:9). This word represents the place where a guard or watchman fulfills his task: “… And appoint watches of the inhabitants of Jerusalem, every one in his watch, and every one to be over against his house” (Neh. 7:3). Someone who guards something keeps “watch” over it: “Mattaniah, and Bakbukiah, … were porters keeping the ward at the thresholds of the gates” (Neh. 12:25). In Job 7:12 mishmâr means “watch” or “guard” in general (over a potentially dangerous criminal): “Am I a sea, or a whale, that thou settest a watch over me?”
Mishmâr can also represent a “place of confinement,” such as a jail: “And he put them in ward in the house of the captain of the guard, into the prison, the place where Joseph was bound” (Gen. 40:3—the first occurrence of the word). Joseph put his brothers “into ward three days” (Gen. 42:17) and thereafter allowed 9 of them to return to Palestine to get Benjamin (an act supposedly proving they were not spies) while 1 of them remained in the Egyptian “prison” (Gen. 42:19). Under Mosaic law there were to be no prisons where people were held for extended periods after being convicted of a crime. Instead, those charged were held for a very short time (sometimes) immediately preceding trial until the trial could be arranged (Lev. 24:12). After the trial the guilty party was killed, punished, fined, or indentured until he worked out his fine. Mishmâr sometimes represents a group of attendants, especially in the temple. In this nuance the word may represent the temple guardunits: “To Shuppim and Hosah the lot came forth westward, with the gate Shallecheth, by the causeway of the going up, ward against ward” (1 Chron. 26:16). However, in Neh. 12:24 the service rendered is the Levitical service in general, therefore, “division corresponding to division.” All these Levitical “divisions” constituted the full services of the temple (Neh. 13:14) The noun mishmereth appears with the same meanings as those just set forth. It can mean a “military watchman or guard” (cf. Neh. 7:3). In Isa. 21:8 the word signifies the place where one keeps watch: “… I am set in my wards whole nights.…” The phrase “to keep watch,” in the sense of to fulfill the function of a watchman or guard, appears with mishmereth in 2 Kings 11:5: “A third part of you that enter in on the sabbath shall even be keepers of the watch of the king’s house.” Mishmereth represents a place of confinement in 2 Sam. 20:3: David put 10 of his concubines who had been defiled by Absalom into a house of confinement (NASB, “under guard”).
Mishmereth often is used to represent a more abstract idea than mishmâr, whereas mishmâr means the units of Levites who served the Lord (perhaps with the exception of Neh. 13:30, where mishmereth may mean “service-unit”). Mishmereth refers to the priestly or Levitical service itself: “Therefore shall ye abide at the door of the tabernacle of the congregation day and night seven days, and keep the charge of the Lord …” (Lev. 8:35). Num. 3:25 speaks of the duties of the Levites in the tent of meeting. The Levites were to “keep the charge of the tabernacle of testimony” (Num. 1:53). The word, therefore, suggests both regularly prescribed act and obligation. The latter idea alone appears in Num. 8:26, where God allows Levites over 50 to serve in extraordinary circumstances, to keep an obligation.
This word often refers to divine obligation or service in general, a non-cultic obligation: “Because that Abraham obeyed my voice, and kept my charge, my commandments, my statutes, and my laws” (Gen. 26:5—the first occurrence of mishmereth; cf. Deut. 11:1).
B. Verb.
Shâmar (שָׁמַר, Strong's #8104), “to keep, watch.” This verb occurs 468 times in the Old Testament. The word means “to watch” in Job 14:16: “For now thou numberest my steps: dost thou not watch over my sin?”