A.T. Robertson Commentary Matthew 27:1

"Now when morning was come, all the chief priests and the elders of the people took counsel against Jesus to put him to death:" — Matthew 27:1 (ASV)

Now when morning was come (πρωιας δε γενομενης). Genitive absolute. After dawn came the Sanhedrin held a formal meeting to condemn Jesus and so ratify the illegal trial during the night (Luke 22:66–71). Luke gives the details of this second ratification consultation. The phrase used,

took counsel (συμβουλιον ελαβον) is a Latin idiom (consilium ceperunt) for συνεβουλευσαντο.