Is the stone
That was rejected
It has become
οὗτός ἐστιν ὁ λίθος ὁ ἐξουθενηθεὶς ὑφ’ ὑμῶν τῶν οἰκοδόμων, ὁ γενόμενος εἰς κεφαλὴν γωνίας.
The author of Acts indicated that Peter said that this Jesus was the stone (οὗτός ἐστιν ὁ λίθος) that was rejected by them (ὁ ἐξουθενηθεὶς ὑφ’ ὑμῶν), the builders (τῶν οἰκοδόμων), that has become (ὁ γενόμενος) the cornerstone or head stone (εἰς κεφαλὴν γωνίας). This is an obvious allusion to Psalm 118:22, a psalm recited at Passover, “The stone that the builders rejected has become the chief cornerstone.” The builders were the Israelite religious leaders who were restoring the Second Temple. Jesus also made a reference to this psalm in the synoptic gospel stories. Matthew, chapter 21:42, and Mark, chapter 12:10-12, are word for word the same. Jesus asked them (Λέγει αὐτοῖς ὁ Ἰησοῦς) if they had read the scriptures (Οὐδέποτε ἀνέγνωτε ἐν ταῖς γραφαῖς) especially Psalm 118, that was also part of the Hallel prayer. Then Jesus quoted a few verses of this Psalm 118: 22-23, about the stone that the builders had rejected (Οὐδέποτε ἀνέγνωτε ἐν ταῖς γραφαῖς), because they probably thought that it was inferior. Now, that very stone has become the cornerstone or key head stone (οὗτος ἐγενήθη εἰς κεφαλὴν γωνίας) of that building. The rejected cornerstone was a hint at Jesus’ own rejection by the Jewish leaders. Luke, chapter 20:17, was more abbreviated. Luke indicated that Jesus looked at them (ὁ δὲ ἐμβλέψας αὐτοῖς). He asked (εἶπεν) what this written biblical text meant (Τί οὖν ἐστιν τὸ γεγραμμένον τοῦτο)? He then quoted Psalm 118, 22 that the very stone that the builders had rejected (Λίθον ὃν ἀπεδοκίμασαν οἱ οἰκοδομοῦντες) had become the chief headstone or the cornerstone (οὗτος ἐγενήθη εἰς κεφαλὴν γωνίας) of the building. Thus, Peter was only repeating what Jesus had said. Have you ever been involved with a cornerstone?