What does God require in the fourth commandment?

Heidelberg Catechism (extended)

The Catechism
Method of Instruction in the Christian Religion
As the Same is Taught in the Reformed Churches and Schools

(with the Scripture references written out)

Note. This Catechism is fully based on the Scriptures. The references to Scripture are indicated in parentheses with a letter. For example, the letter (a) points to the texts (a) placed after the answer.

38. Lord's Day 

Q. 103. What does God require in the fourth commandment? 

A. First, that the ministry of the gospel and the schools be maintained; (a) and that I, especially on the sabbath, that is, on the day of rest, diligently frequent the church of God, (b) to hear his word, (c) to use the sacraments, (d) publicly to call upon the Lord, (e) and contribute to the relief of the poor. (f)
Secondly, that all the days of my life I cease from my evil works, and yield myself to the Lord, to work by his Holy Spirit in me: and thus begin in this life the eternal sabbath. (g) 

(a) Tit.1:5 For this cause left I thee in Crete, that thou shouldest set in order the things that are wanting, and ordain elders in every city, as I had appointed thee: 2 Tim.3:14 But continue thou in the things which thou hast learned and hast been assured of, knowing of whom thou hast learned them; 2 Tim.3:15 And that from a child thou hast known the holy scriptures, which are able to make thee wise unto salvation through faith which is in Christ Jesus. 1 Tim.5:17 Let the elders that rule well be counted worthy of double honour, especially they who labour in the word and doctrine. 1 Cor.9:11 If we have sown unto you spiritual things, is it a great thing if we shall reap your carnal things? 1 Cor.9:13 Do ye not know that they which minister about holy things live of the things of the temple? and they which wait at the altar are partakers with the altar? 1 Cor.9:14 Even so hath the Lord ordained that they which preach the gospel should live of the gospel. 2 Tim.2:2 And the things that thou hast heard of me among many witnesses, the same commit thou to faithful men, who shall be able to teach others also. 

(b) Ps.40:10 I have not hid thy righteousness within my heart; I have declared thy faithfulness and thy salvation: I have not concealed thy lovingkindness and thy truth from the great congregation. Ps.40:11 Withhold not thou thy tender mercies from me, O LORD: let thy lovingkindness and thy truth continually preserve me. Ps.68:27 There is little Benjamin with their ruler, the princes of Judah and their council, the princes of Zebulun, and the princes of Naphtali. Acts 2:42 And they continued stedfastly in the apostles' doctrine and fellowship, and in breaking of bread, and in prayers. Acts 2:46 And they, continuing daily with one accord in the temple, and breaking bread from house to house, did eat their meat with gladness and singleness of heart, 

(c) 1 Tim.4:13 Till I come, give attendance to reading, to exhortation, to doctrine. 1 Cor.14:19 Yet in the church I had rather speak five words with my understanding, that by my voice I might teach others also, than ten thousand words in an unknown tongue. 1 Cor.14:29 Let the prophets speak two or three, and let the other judge. 1 Cor.14:31 For ye may all prophesy one by one, that all may learn, and all may be comforted. 

(d) 1 Cor.11:33 Wherefore, my brethren, when ye come together to eat, tarry one for another. 

(e) 1 Tim.2:1 I exhort therefore, that, first of all, supplications, prayers, intercessions, and giving of thanks, be made for all men; 1 Tim.2:2 For kings, and for all that are in authority; that we may lead a quiet and peaceable life in all godliness and honesty. 1 Tim.2:3 For this is good and acceptable in the sight of God our Saviour; 1 Tim.2:8 I will therefore that men pray every where, lifting up holy hands, without wrath and doubting. 1 Tim.2:9 In like manner also, that women adorn themselves in modest apparel, with shamefacedness and sobriety; not with broided hair, or gold, or pearls, or costly array; 1 Tim.2:10 But (which becometh women professing godliness) with good works. 1 Tim.2:11 Let the woman learn in silence with all subjection. 1 Cor.14:16 Else when thou shalt bless with the spirit, how shall he that occupieth the room of the unlearned say Amen at thy giving of thanks, seeing he understandeth not what thou sayest? 

(f) 1 Cor.16:2 Upon the first day of the week let every one of you lay by him in store, as God hath prospered him, that there be no gatherings when I come. 

(g) Isa.66:23 And it shall come to pass, that from one new moon to another, and from one sabbath to another, shall all flesh come to worship before me, saith the LORD.

Source: http://www.ccel.org/creeds/heidelberg-cat-ext.txt