‘The stone the builders rejected has become the cornerstone. 1
1 tn Or “capstone,” “keystone.” Although these meanings are lexically possible, the imagery in Eph 2:20-22 and 1 Cor 3:11 indicates that the term κεφαλὴ γωνίας (kefalh gwnia") refers to a cornerstone, not a capstone.
sn The stone the builders rejected has become the cornerstone. The use of Ps 118:22-23 and the “stone imagery” as a reference to Christ and his suffering and exaltation is common in the NT (see also Matt 21:42; Luke 20:17; Acts 4:11; 1 Pet 2:6-8; cf. also Eph 2:20). The irony in the use of Ps 118:22-23 in Mark 12:10-11 is that in the OT, Israel was the one rejected (or perhaps her king) by the Gentiles, but in the NT it is Jesus who is rejected by Israel.
2 sn Mention of the inscription is an important detail, because the inscription would normally give the reason for the execution. It shows that Jesus was executed for claiming to be a king. It was also probably written with irony from the executioners’ point of view.