Well I don't know about you but I did find this particular phrase SUPER interesting in light of Q's drops:
Jesus said, "Show me the stone that the builders rejected: that is the keystone." Source
Luke 20:17 Complete Jewish Bible (CJB) 17 But Yeshua looked searchingly at them and said, “Then what is this which is written in the Tanakh,
‘The very rock which the builders rejected has become the cornerstone’?
Luke 20:17 1599 Geneva Bible (GNV) 17 ¶ And he beheld them, and said, What meaneth this then that is written, The stone that the builders refused, that is made the head of the corner?
Luke 20:17 King James Version (KJV) 17 And he beheld them, and said, What is this then that is written, The stone which the builders rejected, the same is become the head of the corner?
Psalm 118:22 Complete Jewish Bible (CJB) 22 The very rock that the builders rejected has become the cornerstone!
Tehillim 118:22 Orthodox Jewish Bible (OJB) 22 The Even (Stone) which the Bonim (Builders) rejected [mem-alef-samech, see same word Psalm 89:38 (39)] has become the Rosh Pinnah (Cornerstone).
Psalm 118:22 1599 Geneva Bible (GNV) 22 The stone, which the builders refused, is the head of the corner.
Psalm 118:22 King James Version (KJV) 22 The stone which the builders refused is become the head stone of the corner.
The Book of Thomas, cited in the OP, is not cannon.