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
isa 56:1THE PREPARATION NEEDED ON THE PART OF THOSE WHO WISH TO BE ADMITTED TO THE KINGDOM OF GOD. (Isa 56:1-12)
judgment--equity. John the Baptist preached similarly a return to righteousness, as needed to prepare men for Messiah's first coming (Luk 3:3, Luk 3:8-14). So it shall be before the second coming (Mal 4:4-6).
near to come-- (Mat 3:2; Mat 4:17), also as to the second coming (Isa 62:10-11; Luk 21:28, Luk 21:31; Rom 13:11-12; Heb 10:25).
righteousness--answering to "salvation" in the parallel clause; therefore it means righteousness which bringeth salvation (Isa 46:13; Rom 3:25-26).
isa 56:2(Luk 12:43).
the man--Hebrew, enosh, "a man in humble life," in contradistinction to Hebrew, ish, "one of high rank." Even the humblest, as "the stranger" and "the eunuch" (Isa 56:4, Isa 56:6), are admissible to these privileges.
this . . . it--what follows: "keeping the Sabbath," &c. (Isa 58:13-14; Eze 20:12). A proof that the Sabbath, in the spirit of its obligation, was to be binding under the Gospel (Isa 66:23). That gospel times are referred to is plain, from the blessing not being pronounced on the man who observed the sacrificial ritual of the Jewish law.
layeth hold--image from one grasping firmly some precious object which he is afraid of having forcibly snatched from him. The "Sabbath" here includes all the ordinances of divine worship under the new gospel law.
keepeth . . . hand . . . from . . . evil--The observance of the second table of the law; as the "Sabbath" referred to the first table. Together, they form the whole duty of man, the worship of God and a holy life.
isa 56:3God welcomes all believers, without distinction of persons, under the new economy (Act 10:34-35).
joined . . . to . . . Lord-- (Num 18:4, Num 18:7). "Proselytes."
separated--Proselytes from the Gentiles were not admitted to the same privileges as native Israelites. This barrier between Jews and Gentiles was to be broken down (Eph 2:14-16).
eunuch-- (Act 8:27, &c.). Eunuchs were chamberlains over harems, or court ministers in general.
dry tree--barren (compare Luk 23:31); not admissible into the congregation of Israel (Deu 23:1-3). Under the Gospel the eunuch and stranger should be released from religious and civil disabilities.
isa 56:4please me--sacrifice their own pleasure to mine.
take hold--so "layeth hold" (see on Isa 56:2).
isa 56:5in mine house--the temple, the emblem of the Church (Ti1 3:15). They shall no longer be confined as proselytes were, to the outer court, but shall be admitted "into the holiest" (Heb 10:19-20).
a place--literally, "a hand."
than of sons--Though the eunuch is barren of children (Isa 56:3), I will give him a more lasting name than that of being father of sons and daughters (regarded as a high honor among the Hebrews) (Joh 1:12; Joh 10:3; Jo1 3:1; Rev 2:17; Rev 3:12).
isa 56:6join . . . Lord-- (Jer 50:6). Conditions of admission to the privileges of adoption.
isa 56:7Even them-- (Eph 2:11-13).
to my holy mountain--Jerusalem, the seat of the Lord's throne in His coming kingdom (Isa 2:2; Jer 3:17).
joyful-- (Rom 5:11).
burnt offerings . . . sacrifices--spiritual, of which the literal were types (Rom 12:1; Heb 13:15; Pe1 2:5).
accepted-- (Eph 1:6).
altar-- (Heb 13:10), spiritually, the Cross of Christ, which sanctifies our sacrifices of prayer and praise.
house . . . for all people--or rather, "peoples." No longer restricted to one favored people (Mal 1:11; Joh 4:21, Joh 4:23; Ti1 2:8). To be fully realized at the second coming (Isa 2:2-4). No longer literal, but spiritual sacrifice, namely, "prayer" shall be offered (Psa 141:2; Psa 51:17; Mal 1:11; Mat 21:13).
isa 56:8Jehovah will not only restore the scattered outcasts of Israel (Isa 11:12; Psa 147:2) to their own land, but "will gather others ('strangers') to him (Israel), besides those gathered" (Margin, "to his gathered"; that is, in addition to the Israelites collected from their dispersion), (Joh 10:16; Eph 1:10; Eph 2:19).
isa 56:9beasts--Gentile idolatrous nations hostile to the Jews, summoned by God to chastise them (Jer 12:7-9; Jer 50:17; Eze 34:5): the Chaldeans and subsequently the Romans. The mention of the "outcasts of Israel" (Isa 56:8) brings in view the outcasting, caused by the sins of their rulers (Isa 56:10-12).
to devour--namely, Israel.
isa 56:10His watchmen--Israel's spiritual leaders (Isa 62:6; Eze 3:17).
dumb dogs--image from bad shepherds' watchdogs, which fail to give notice, by barking, of the approach of wild beasts.
blind-- (Mat 23:16).
sleeping, lying down--rather, "dreamers, sluggards" [LOWTH]. Not merely sleeping inactive, but under visionary delusions.
loving to slumber--not merely slumbering involuntarily, but loving it.
isa 56:11greedy--literally, "strong" (that is, insatiable) in appetite (Eze 34:2-3; Mic 3:11).
cannot understand--unable to comprehend the wants of the people, spiritually: so Isa 56:10, "cannot bark."
look to . . . own way--that is, their own selfish interests; not to the spiritual welfare of the people (Jer 6:13; Eze 22:27).
from his quarter--rather, "from the highest to the lowest" [LOWTH]. "From his quarter"; that is, from one end to the other of them, one and all (Gen 19:4).
isa 56:12fetch wine--language of the national teachers challenging one another to drink. BARNES translates, "I will take another cup" (Isa 5:11).
to-morrow, &c.--Their self-indulgence was habitual and intentional: not merely they drink, but they mean to continue so.
In the midst of the excesses of the unfaithful watchmen (Isa 56:10-12), most of the few that are godly perish: partly by vexation at the prevailing ungodliness; partly by violent death in persecution: prophetical of the persecuting times of Manasseh, before God's judgments in causing the captivity in Babylon; and again those in the last age of the Church, before the final judgments on the apostasy (Kg2 21:16; Mat 23:29-35, Mat 23:37; Rev 11:17). The Hebrew for "perisheth," and "is taken away," expresses a violent death (Mic 7:2).