They continued steadfastly in the apostles' doctrine - They received it, retained it, and acted on its principles.

And fellowship - Κοινωνιᾳ, community; meaning association for religious and spiritual purposes, The community of goods cannot be meant; for this is mentioned Acts 2:44, Acts 2:45, where it is said, they had all things common.

And in breaking of bread - Whether this means the holy eucharist, or their common meals, it is difficult to say. The Syriac understands it of the former. Breaking of bread was that act which preceded a feast or meal, and which was performed by the master of the house, when he pronounced the blessing - what we would call grace before meat. See the form on Matthew 26:26 (note).

And in prayers - In supplications to God for an increase of grace and life in their own souls; for establishment in the truth which they had received, and for the extension of the kingdom of Christ in the salvation of men. Behold the employment of the primitive and apostolic Church.

1. They were builded up on the foundation of the prophets and apostles, Jesus Christ himself being the corner stone.

2. They continued steadfastly in that doctrine which they had so evidently received from God.

3. They were separated from the world, and lived in a holy Christian fellowship, strengthening and building up each other in their most holy faith.

4. They were frequent in breaking bread; in remembrance that Jesus Christ died for them.

5. They continued in prayers; knowing that they could be no longer faithful than while they were upheld by their God; and knowing also that they could not expect his grace to support them, unless they humbly and earnestly prayed for its continuance.

they.

Acts 2:46 And they, continuing daily with one accord in the temple, and breaking bread from house to house...

Acts 11:23 Who, when he came, and had seen the grace of God, was glad, and exhorted them all...

Acts 14:22 Confirming the souls of the disciples, and exhorting them to continue in the faith...

Mark 4:16,17 And these are they likewise which are sown on stony ground; who, when they have heard the word, immediately receive it with gladness...

John 8:31,32 Then said Jesus to those Jews which believed on him, If you continue in my word, then are you my disciples indeed...

1 Corinthians 11:2 Now I praise you, brothers, that you remember me in all things, and keep the ordinances, as I delivered them to you.

Galatians 1:6 I marvel that you are so soon removed from him that called you into the grace of Christ to another gospel:

Ephesians 2:20 And are built on the foundation of the apostles and prophets, Jesus Christ himself being the chief corner stone;

Colossians 1:23 If you continue in the faith grounded and settled, and be not moved away from the hope of the gospel, which you have heard...

2 Timothy 3:14 But continue you in the things which you have learned and have been assured of, knowing of whom you have learned them;

Hebrews 10:39 But we are not of them who draw back to perdition; but of them that believe to the saving of the soul.

2 Peter 3:1,2,17,18 This second letter, beloved, I now write to you; in both which I stir up your pure minds by way of remembrance...

1 John 2:19 They went out from us, but they were not of us; for if they had been of us, they would no doubt have continued with us...

fellowship.

Acts 4:23 And being let go, they went to their own company, and reported all that the chief priests and elders had said to them.

Acts 5:12-14 And by the hands of the apostles were many signs and wonders worked among the people...

1 John 1:3,7 That which we have seen and heard declare we to you, that you also may have fellowship with us...

in breaking.

Acts 20:7,11 And on the first day of the week, when the disciples came together to break bread, Paul preached to them, ready to depart on the morrow...

1 Corinthians 10:16,17,21 The cup of blessing which we bless, is it not the communion of the blood of Christ? The bread which we break...

1 Corinthians 11:20-26 When you come together therefore into one place, this is not to eat the Lord's supper...

and in prayers.

Acts 1:14 These all continued with one accord in prayer and supplication, with the women, and Mary the mother of Jesus, and with his brothers.

Acts 4:31 And when they had prayed, the place was shaken where they were assembled together; and they were all filled with the Holy Ghost...

Acts 6:4 But we will give ourselves continually to prayer, and to the ministry of the word.

Romans 12:12 Rejoicing in hope; patient in tribulation; continuing instant in prayer;

Ephesians 6:18 Praying always with all prayer and supplication in the Spirit...

Colossians 4:2 Continue in prayer, and watch in the same with thanksgiving;

Hebrews 10:25 Not forsaking the assembling of ourselves together, as the manner of some is; but exhorting one another: and so much the more...

Jude 1:20 But you, beloved, building up yourselves on your most holy faith, praying in the Holy Ghost,

Pentecost
Text: Acts 2, 1-13. 1 And when the day of Pentecost was now come, they were all together in one place. 2 And suddenly there came from heaven a sound as of the rushing of a mighty wind, and it filled all the house where they were sitting. 3 And there appeared unto them tongues parting asunder, like as of fire; and it sat upon each one of them. 4 And they were all filled with the Holy Spirit, and began to speak with other tongues, as the Spirit gave them utterance. 5 Now there were dwelling at Jerusalem …
Martin Luther—Epistle Sermons, Vol. II

Peter's First Sermon
'This Jesus hath God raised up, whereof we all are witnesses. 33. Therefore being by the right hand of God exalted, and having received of the Father the promise of the Holy Ghost, He hath shed forth this, which ye now see and hear. 34. For David is not ascended into the heavens: but he saith himself, The Lord said unto my Lord, Sit Thou on My right hand, 35. Until I make Thy foes Thy footstool. 36. Therefore let all the house of Israel know assuredly, that God hath made that same Jesus, whom ye …
Alexander Maclaren—Expositions of Holy Scripture: The Acts

The Historical and Spiritual Causes of the Death of Christ
"Him, being by the determined will and foreknowledge of God given up, through the hand of lawless men, ye affixed to a cross and slew."--ACTS II. 23. St. Paul places this in the very forefront of that gospel which, as it had been delivered to him, so he in his turn had delivered to the Corinthians, that "Christ died for our sins." Neglecting all, deeper interpretations of this, it is at least clear that in the apostle's mind there was the closest and most intimate connexion between the death of …
J. H. Beibitz—Gloria Crucis