Jamieson, Fausset and Brown on Daniel 2:12-13

12-13. Daniel and his companions do not seem to have been actually numbered among the Magi or Chaldeans, and so were not summoned before the king. Providence ordered it so that all mere human wisdom should be shown vain before His divine power, through His servant, was put forth. Da 2:24 shows that the decree for slaying the wise men had not been actually executed when Daniel interposed.