Complete Commentary on the Whole Bible, by Matthew Henry, at sacred-texts.com
(Isa 56:1, Isa 56:2) A charge to keep the Divine precepts.
(Isa 56:3-8) Blessings promised.
(Isa 56:9-12) Reproof to the careless watchmen, the teachers and rulers of the Jews.
The Lord tells us what are his expectations of duty from us. Be honest and just in all dealings. Also strictly observe the sabbath day. To have the blessing of God upon employments all the week, make conscience of keeping the sabbath holy. Have nothing to do with sin. Blessed is the man that keeps his hand from all things displeasing to God and hurtful to his own soul. Those who, through the Spirit, wait for the hope of righteousness by faith, will be found walking in ways of holy obedience.
Unbelief often suggests things to discourage believers, against which God has expressly guarded. Spiritual blessings are unspeakably better than having sons and daughters; for children are a care, and may prove a grief and shame, but the blessings we partake of in God's house, are comforts which cannot be made bitter. Those who love the Lord truly, will serve him faithfully, and then his commandments are not grievous. Three things are promised. Assistance: I will not only bid them welcome, but incline them to come. Acceptance, and comfort: though they came mourning to the house of prayer, they shall go away rejoicing. They shall find ease by casting their cares and burdens upon God. Many a sorrowful spirit has been made joyful in the house of prayer. The Gentiles shall be one body with the Jews, that, as Christ says, Joh 10:16, there may be one fold and one Shepherd. Thanks be to God that none are separated from him except by wilful sin and unbelief; and if we come to him, we shall be accepted through the sacrifice of our great High Priest.
Desolating judgments are called for; and this severe rebuke of the rulers and teachers of the Jewish church, is applicable to other ages and places. It is bad with a people when their shepherds slumber, and are eager after the world. Let us pray the Great Shepherd to send us pastors after his own heart, who will feed us with knowledge, that we may rejoice in his holy name, and that believers may be daily added to the church.