Not forsaking the assembling of ourselves together, as the manner of some is; but exhorting one another: and so much the more, as ye see the day approaching. Not forsaking the assembling of ourselves - Επισυναγωγην ἑαυτων. Whether this means public or private worship is hard to say; but as the word is but once more used in the New Testament, (2 Thessalonians 2:1), and there means the gathering together of the redeemed of the Lord at the day of judgment, it is as likely that it means here private religious meetings, for the purpose of mutual exhortation: and this sense appears the more natural here, because it is evident that the Church was now in a state of persecution, and therefore their meetings were most probably held in private. For fear of persecution, it seems as if some had deserted these meetings, καθως εθος τισιν, as the custom of certain persons is. They had given up these strengthening and instructive means, and the others were in danger of following their example.
The day approaching - Την ἡμεραν· That day - the time in which God would come and pour out his judgments on the Jewish nation. We may also apply it to the day of death and the day of judgment. Both of these are approaching to every human being. He who wishes to be found ready will carefully use every means of grace, and particularly the communion of saints, if there be even but two or three in the place where he lives, who statedly meet together in the name of Christ. Those who relinquish Christian communion are in a backsliding state; those who backslide are in danger of apostasy. To prevent this latter, the apostle speaks the awful words following. See at the end of this chapter (Hebrews 10:39 (note)).