(Which he had promised afore by his prophets in the holy scriptures,)
the gospel he promised beforehand through his prophets in the Holy Scriptures
ὃ προεπηγγείλατο διὰ τῶν προφητῶν αὐτοῦ ἐν γραφαῖς ἁγίαις,
o proepēggeilato dia tōn prophētōn aytoy en graphais agiais,