Charles H. Spurgeon on Psalms 133:1

Pleasant. It is a pleasant thing for the saints and people of God to agree together; for the same word which is used here for "pleasant", is used also in the Hebrew for a harmony of music, such as when they rise to the highest strains of the viol, when the strings are all put in order to make up a harmony; so pleasant is it, such pleasantness is there in the saints' agreement. The same word is used also in the Hebrew for the pleasantness of a corn field. When a field is clothed with corn, though it be cut down, yet it is very pleasant, oh, how pleasant is it; and such is the saints' agreement. The same word in the Psalmist is used also for the sweetness of honey, and of sweet things in opposition to bitter things. And thus you see the pleasantness of it, by its being compared to the harmony of music, to the corn field, to the sweetness of honey, to the precious ointment that ran down Aaron's beard, and to the dew that fell upon Hermort and the hills of Zion: and all this to discover the pleasantness, profitableness, and sweetness of the saints' agreement. It is a pleasant thing to behold the sun, but it is much more pleasant to behold the saints' agreement and unity among themselves. —William Bridge.