Mission from the point of view of Old Testament Israel

One of the clearest things to me as you read the Old Testament is how central it is to God's plans that his people be a blessing to all the nations. Mission is too often spoken about in churches only from texts like Matthew 28 and Acts 1. But the whole Bible has this consistent them, and Wright surveys the Pentateuch, the Psalms and the Prophets to show this.

As a caveat, I'm increasingly wondering whether the nagging voice in the back of my head about what's missing sort of begins to become clear here: the continuity of the theme of God's people, i.e. the church, is a bit shaky in his framework. We'll see. But I just read this excellent line:

'The recipients of the Abrahamic blessing [Gen 12 etc] become the agents of it. The principle that those those who are blessed are to te the means of blessing others is not confined to Israel alone, as if Israel would forever be the exclusive transmitters of a blessing that could only be passively received by the rest from their hand. No the Abrahamic promises is a self-replicating gene. Those who received it are immediately transformed into those whose privilege and mission it is to pass it on to others.' (p 236)

What is it to be blessed in Abraham?