“(Now that he ascended, what is it but that he also descended first into the lower parts of the earth?”
King James Version (KJV)
4:9 Now this expression, He ascended, what is it, but that he descended - That is, does it not imply, that he descended first? Certainly it does, on the supposition of his being God. Otherwise it would not: since all the saints will ascend to heaven, though none of them descended thence. Into the lower parts of the earth - So the womb is called, #Psa 139:15|; the grave, #Psa 63:9|.
Eph 4:9 Now that he ascended . . . also descended first. Paul, in applying this to Christ, shows that it implies that he must have descended from heaven, before his ascension to heaven. This must necessarily follow, if the one ascending is divine, and has a home in heaven, as Ps 68:18 indicates.