Hebrews 8:8-13
For God found fault with the Israelites [or, possibly with the first Agreement], saying [Jer. 31:31ff], "Look, the Lord says, the time will come when I will make a New Agreement with the people of Israel and with the people of Judah.
Hebrews 11:40
because God had planned to give us something better [than they got], so that they would not be complete without us. [Note: The idea here is that these faithful people of Old Testament times did not receive the fullest of blessings until Christ came to make them available to both them and us together].
1 John 5:20
And [in addition], we know that the Son of God has come [in a physical body, See 4:2] and has given us understanding, so that we can know the True One [i.e., God], and that we are in [fellowship with] the True One, even His Son Jesus Christ. This Son is the true God and eternal life.