{That they might catch him in talk} (hina auton agreus(9373)in
log(9369)). Ingressive aorist subjunctive. The verb is late from
agra (a hunt or catching). It appears in the LXX and papyri.
Here alone in the N.T.  Lu 20:20  has the same idea, "that they
may take hold of his speech" (epilab(936e)tai autou logon) while
 Mt 22:15  uses pagideus(9373)in (to snare or trap). See discussion
in Matthew. We have seen the scribes and Pharisees trying to do
this very thing before ( Lu 11:33f. ). Mark and Matthew note here
the combination of Pharisees and Herodians as Mark did in  3:6 .
Matthew speaks of "disciples" or pupils of the Pharisees while
Luke calls them "spies" (enkathetous).