Behold, how good and how pleasant [it is]
Aben Ezra thinks the word thing should be supplied; the thing is what follows;
for brethren to dwell together in unity:
which the Targum interprets of Zion and Jerusalem, as two brethren; Aben Ezra of the priests; Kimchi of the King Messiah and the priest; and Jarchi, and Kimchi's father, of the Israelites; which is best of all, especially of those who are Israelites indeed; for this is not to be understood of all mankind, who are in some sense brethren, being all of one blood, and among whom peace is to be cultivated; nor merely of those of the same nation, under one and the same government, who should endeavour to live peaceably and quietly; nor of brethren in a strict natural state, who belong to the same family, and are of the same parents, and should be kindly affectioned one to another; but rather of such who are so in a spiritual sense, who have God for their fatherly adoption and regeneration, are related to Christ the firstborn among many brethren, and are members one of another, in the same church state; all which are a reason why they should love as brethren, and endeavour to keep the unity of the Spirit in the bond of peace, ( Matthew 23:8 ) ( Ephesians 4:3 Ephesians 4:6 ) ( 1 Peter 2:17 ) ( 3:8 ) ( Hebrews 13:1 ) ; and "to dwell together in unity"; even as one man, as if one soul actuated them all; it is not only to dwell and abide in the house of God, where they have all a name and a place; but to associate together there, to go up to the house of God in company, and with delight to join together in acts of religious worship; to serve the Lord with one consent, with one mind and mouth to glorify God, and to be of one accord, having the same love; and to do all kind and good offices one to another in the most hearty and cordial manner; serving each other in love, bearing one another's burdens, sympathizing with each other in all circumstances, forgiving each other offences committed, praying with one another, and building up each other in their most holy faith, stirring up one another to love and to good works: now this is both "good" and "pleasant"; it is good, as being according to the will of God, the new command of Christ; what evidences the truth of regeneration, and of being the disciples of Christ; what makes the communion of saints comfortable and edifying, and without which a profession of religion is good for nothing: and it is pleasant to God and Christ, to angels and men, to the ministers of the Gospel, and to all about them and in a connection with them; and it is this which makes any particular dispensation in time delightful and agreeable; as the first times of the Gospel, and the latter day glory, the Philadelphian church state, which has its name from brotherly love; yea, it will be the glory and delight of heaven. Now this is ushered in with a note of attention and admiration, "behold", and with a note of exclamation, "how"; the psalmist pointing at some instance or instances of this kind, which were very amiable, and worthy of imitation; and suggesting that such a case is rare and wonderful, and inexpressibly good, profitable, and pleasant. Gussetius F26 renders it, "how good is the sabbatism of brethren, even gathered together"; for the exercise of religion, prayer, praise
F26 Ebr. Comment. p. 829.