1 Timothy 1:7

θέλοντες εἶναι νομοδιδάσκαλοι. Desiring to be (i.e. almost claiming to be) teachers of the law, sc. of the Mosaic law. The false teaching had its roots in Judaism, and the intention of its exponents was good; they failed in their aims for the reasons now to be explained.

μὴ νοοῦντες μήτε ἃ λέγουσιν κ.τ.λ. Understanding neither what they say, nor the subjects concerning which they make confident assertions. Their ματαιολογία was, in many instances, devoid of meaning (μὴ νοοῦντες κ.τ.λ.); and they did not understand the principles underlying the Mosaic law which they professed to expound (μήτε περὶ τίνων κ.τ.λ.). Cp. 2 Timothy 2:7 νόει ὃ λέγω. διαβεβαιοῦσθαι is found in the Greek Bible only here and at Titus 3:8 περὶ τούτων βούλομαί σε διαβεβαιοῦσθαι; it signifies positive affirmation and entire confidence on the part of the speaker.