Augustine of Hippo — as excerpted in the Catena Aurea on John 6:35-40

“(Tr. xxv. 19) See how the twofold resurrection is expressed here. He who cometh to Me, shall forthwith rise again; by becoming humble, and a member of Me. But then He proceeds; But I will raise him up at the last day. To explain the words, All that the Father hath given Me, and, I should lose nothing, He adds; And this is the will of Him that hath sent Me, that every one which seeth the Son, and believeth on Him, may have everlasting life: and I will raise him up at the last day. Above He said, Whoso heareth My word, and believeth on Him that sent Me: (c. 5:24) now it is, Every one which seeth the Son, and believeth on Him. He does not say, believe on the Father, because it is the same thing to believe on the Father, and on the Son; for as the Father hath life in Himself, even so hath He given to the Son to have life in Himself; and again, That whoso seeth the Son and believeth on Him, should have everlasting life: i. e. by believing, by passing over to life, as at the first resurrection. But this is only the first resurrection, He alludes to the second when He says, And I will raise him up at the last day.”