Malachi 4:5 (3:22 LXX)
Behold, I am going to send you Elijah the prophet before the great and foudroyant day of the Lord shall come.
Joel 2:31 (3:4 LXX)
The sun will be turned into darkness and the moon into blood, before the great and foudroyant day of the Lord shall come.
Acts 2:20
The sun will be turned into darkness and the moon into blood, before the great and foudroyant day of the Lord shall come.
Malachi 4:5 (3:22 LXX)
πρὶν ἐλθεῖν ἡμέραν κυρίου τὴν μεγάλην καὶ ἐπιφαν
Joel 2:31 (3:4 LXX)
πρὶν ἐλθεῖν ἡμέραν κυρίου τὴν μεγάλην καὶ ἐπιφανῆ
Acts 2:20
πρὶν ἐλθεῖν ἡμέραν κυρίου τὴν μεγάλην καὶ ἐπιφανῆ
It reads exactly the same in all three passages in boldface above in the Greek. "The Lord" is in reference to Jesus in all three passages above.
Acts 2:20-21
(20) The sun shall be turned into darkness, and the moon into blood, before the coming of the great and foudroyant day of the Lord.
(21) And it shall come to pass, that whosoever shall call on the Name of the Lord shall be saved.
Since "the Lord" in Acts 2:21 refers to the Lord Jesus (see the bottom of this thread) this points to "the Lord" in Acts 2:20 also being in reference to the Lord Jesus.
Furthermore, notice how Peter once again makes mention of the coming of the day of the Lord in reference to Jesus
in 2 Peter - the speaker in Acts 2:20-21 is Peter (recorded by Luke).
2 Peter 3:2-4, 10
(2) that you should remember the words spoken beforehand by the holy prophets and the commandment of the Lord and Savior spoken by your apostles. (cf. 'the apostles of our Lord Jesus Christ,' Jude 17)
(3) Know this first of all, that in the last days mockers will come with their mocking, following after their own lusts,
(4) and saying, “Where is the promise of His coming? For ever since the fathers fell asleep, all continues just as it was from the beginning of creation.”
(10) But the day of the Lord will come like a thief, in which the heavens will pass away with a roar and the elements will be destroyed with intense heat, and the earth and its works will be burned up.
"His coming" in v. 4 refers back to the Lord Jesus from verse 2.
In v. 10 the Lord's coming is referred to again which is also in reference to Jesus (cf. 1 Thessalonians 5:2).
Acts 2:20 is from Joel 2:31 (3:4 LXX)
and
Acts 2:21 is from Joel 2:32 (3:5 LXX)
Acts 2:21 was already addressed here:
Behold, I am going to send you Elijah the prophet before the great and foudroyant day of the Lord shall come.
Joel 2:31 (3:4 LXX)
The sun will be turned into darkness and the moon into blood, before the great and foudroyant day of the Lord shall come.
Acts 2:20
The sun will be turned into darkness and the moon into blood, before the great and foudroyant day of the Lord shall come.
Malachi 4:5 (3:22 LXX)
πρὶν ἐλθεῖν ἡμέραν κυρίου τὴν μεγάλην καὶ ἐπιφαν
Joel 2:31 (3:4 LXX)
πρὶν ἐλθεῖν ἡμέραν κυρίου τὴν μεγάλην καὶ ἐπιφανῆ
Acts 2:20
πρὶν ἐλθεῖν ἡμέραν κυρίου τὴν μεγάλην καὶ ἐπιφανῆ
It reads exactly the same in all three passages in boldface above in the Greek. "The Lord" is in reference to Jesus in all three passages above.
Acts 2:20-21
(20) The sun shall be turned into darkness, and the moon into blood, before the coming of the great and foudroyant day of the Lord.
(21) And it shall come to pass, that whosoever shall call on the Name of the Lord shall be saved.
Since "the Lord" in Acts 2:21 refers to the Lord Jesus (see the bottom of this thread) this points to "the Lord" in Acts 2:20 also being in reference to the Lord Jesus.
Furthermore, notice how Peter once again makes mention of the coming of the day of the Lord in reference to Jesus
in 2 Peter - the speaker in Acts 2:20-21 is Peter (recorded by Luke).
2 Peter 3:2-4, 10
(2) that you should remember the words spoken beforehand by the holy prophets and the commandment of the Lord and Savior spoken by your apostles. (cf. 'the apostles of our Lord Jesus Christ,' Jude 17)
(3) Know this first of all, that in the last days mockers will come with their mocking, following after their own lusts,
(4) and saying, “Where is the promise of His coming? For ever since the fathers fell asleep, all continues just as it was from the beginning of creation.”
(10) But the day of the Lord will come like a thief, in which the heavens will pass away with a roar and the elements will be destroyed with intense heat, and the earth and its works will be burned up.
"His coming" in v. 4 refers back to the Lord Jesus from verse 2.
In v. 10 the Lord's coming is referred to again which is also in reference to Jesus (cf. 1 Thessalonians 5:2).
Acts 2:20 is from Joel 2:31 (3:4 LXX)
and
Acts 2:21 is from Joel 2:32 (3:5 LXX)
Acts 2:21 was already addressed here:
