A.T. Robertson Commentary Romans 9:29

"And, as Isaiah hath said before, Except the Lord of Sabaoth had left us a seed, We had become as Sodom, and had been made like unto Gomorrah." — Romans 9:29 (ASV)

Hath said before (προειρηκεν). Perfect active indicative of προειπον (defective verb). Stands on record in Isa 1:9.

Had left (εγκατελιπεν). Second aorist active indicative of old verb εγκαταλειπω, to leave behind. Condition of second class, determined as unfulfilled, with αν εγενηθημεν and αν ωμοιωθημεν as the conclusions (both first aorist passives of γινομα and ομοιοω, common verbs).

A seed (σπερμα). The remnant of verse 27.