Below are the words of Robert Shaw in his exposition of the Westminster Confession of Faith regarding the matter of family worship.
The words are to be found in his exposition of chapter 21, section 6 which reads:
Neither prayer, nor any other part of religious worship, is now, under the gospel, either tied unto, or made more acceptable to, any place in which it is performed, or towards which it is directed: but God is to be worshipped everywhere in spirit and in truth; as in private families daily, and in secret each one by himself, so more solemnly in the public assemblies, which are not carelessly or wilfully to be neglected or forsaken, when God, by his Word or providence, calleth thereunto.
Robert Shaw says:
Religious worship ought to be performed in private families daily. This is a duty which the light of nature very plainly teaches. And the heathens will rise up in judgment against the prayerless families of professed Christians; for besides their tutelar deities, who were supposed to preside over cities and nations, and who had public honours paid to them in that character, they had their household gods, whom every private family worshipped at home as their immediate guardians and benefactors.
But the light of Scripture gives a more clear discovery of the obligation to this duty. It is recommended by the example of the saints recorded in Scripture; and good examples as really bind us to the duty as express precepts. We find Abraham rearing up altars wherever he came; and his attention to family religion was expressly commended by God, Gen. 18:19. We have the examples of Joshua (24:15); of Job (1:6); and of David, 2 Sam. 6:20. But we have a still more engaging example of family worship on record in Scripture than any of these, even the example of our Saviour himself, who, though he had no house of his own, yet he had a family, Matt. 10:25. Now we find him retiring from the crowd that followed him, and praying with his own family, Luke 9:18: "As he was alone praying, his disciples were with him."
The practice of family worship tends to promote even the temporal prosperity of families; for it is the blessing of God that maketh rich and prosperous; and what more likely way to obtain that blessing, than for a whole family to join in prayer and ask it daily of God? Prov. 3:33. Much more does family worship tend to promote the spiritual and eternal interests of families; while it is also the most effectual means to propagate religion from generation to generation.
On the other hand, the neglect of this duty will bring the curse of God upon families; for "the curse of the Lord is in the house of the wicked," Prov. 3:33. How awful is that text, Jer. 10:25: "Pour out thy fury upon the heathen that know thee not, and upon the families that call not upon thy name." Let the head of every family, then, adopt the excellent resolution of Joshua: "As for me and my house, we will serve the Lord".