laying wait for him, to catch something out of his mouth.

And watching him, for a chance to get something from his words which might be used against him.

ενεδρευοντες αυτον και ζητουντες να αρπασωσι τι απο του στοματος αυτου, δια να κατηγορησωσιν αυτον.

Laying wait for him, and seeking to catch something out of his mouth, that they might accuse him.