6. οὖ ἐξέχεεν ἐφʼ ἡμᾶς πλουσίως, which, sc. the Holy Spirit, He, sc. God the Father, the subject of the whole sentence, poured out upon us richly.
By the ordinary rules of attraction, οὖ is attracted into the case of the immediately preceding genitive, to which it refers.
The verb ἐκχέειν is the verb used to signify the outpouring of the Holy Spirit in Act 2:17 (Joe 3:1) and 33. In the former passage the occasion was the Day of Pentecost; here the reference is to that outpouring of grace in baptism which is always pledged to the penitent and faithful soul: cp. Act 2:38.
διὰ Ἰησοῦ Χριστοῦ τοῦ σωτῆρος ἡμῶν. This is closely connected with the preceding ἐξέχεεν and not, of course, with the more distant ἔσωσεν of Tit 3:5. The co-operation of all three Persons of the Blessed Trinity in the work of grace is tersely and pregnantly expressed in this short verse. If the Father is σωτήρ (Tit 3:4, see on 1Ti 1:1), so also the Son is σωτήρ, in a sense undreamed of under the Old Covenant.