Er.. the text says that Abraham believed God on the matter of provision of a much yearned for heir.
There is nothing in the text about faith in some future Messiah. Righteousness (which you seem was obtained through Christ) from faith expressed re: God's then promise regarding heir provision
You seem to be reading a theology into the text.
John 8:56-59
Your father Abraham rejoiced at the thought of seeing my day; he saw it and was glad.”
57 “You are not yet fifty years old,” they said to him, “and you have seen Abraham!”
58 “Very truly I tell you,” Jesus answered, “before Abraham was born, I am!” 59 At this, they picked up stones to stone him, but Jesus hid himself, slipping away from the temple grounds.
1 Peter 1:10-12
Concerning this salvation,
the prophets, who spoke of the grace that was to come to you, searched intently and with the greatest care, 11 trying to find out the time and circumstances to which
the Spirit of Christ in them was pointing when he predicted the sufferings of the Messiah and the glories that would follow. 12 It was revealed to them that they were not serving themselves but you, when they spoke of the things that have now been told you by those who have preached the gospel to you by the Holy Spirit sent from heaven. Even angels long to look into these things.
Anything else you want to know about the OT saints knowing about the coming of the future Messiah is what they looked forward to ?
hope this helps !!!