Romans 4:21,22

“ Being fully convinced that, what He has promised, he is able also to perform. Wherefore also righteousness was imputed to him. ” Πληροφορεῖν, to fill a vessel to the brim; this word used in the passive applies to a man filled with a conviction which leaves no place in his heart for the least doubt. It is the opposite of the διακρίνεσθαι, to be inwardly divided, of Romans 4:20. If the relation between the two participles: giving glory and being convinced, is as we have said, we should probably omit the καί, and, which begins this verse in the Alex. and Byz., and prefer the Greco-Latin reading which rejects it.

As to the καί, also, before ποιῆσαι, to do, it well expresses the inseparable relation which the moral perfection of God establishes between His saying and His doing. If His power were not equal to the height of His promise, He would not promise.