After seeing the place of prayer in this new group of believers (Acts 1.12-14) we now see the place of Scripture among them in vv.15-20.
Peter takes on a leadership role within the group and [stands] up among the brothers to speak. He says, simply, that Scripture [has] to be fulfilled. Their next move as a new movement will be directed by Scripture and what the Lord wants, not what they want. For the first time in the New Testament we see Peter quoting Scripture (Psalm 69 and Psalm 109) and the point is made that the Holy Spirit spoke beforehand by the mouth of David concerning Judas. The believers resolve to find a replacement for Judas not because they want to, but because Scripture says they should.
What a great point for us to ponder today. Are we acting and reacting in ways that we feel we should, are we doing what seems right in our own eyes or what the world expects us to do? Or, as we see those here in Acts 1.15-20 doing, are we making our next move directed by Scripture and what the Lord wants? Peter and the rest of the group believed that Scripture shows the way. If you are working through a decision today, if you are looking for guidance, turn to the Word to see your way.