Romans 15:12
And again, Esaias saith, There shall be a root of Jesse, and he that shall rise to reign over the Gentiles; in him shall the Gentiles trust. And again, Esaias saith, There shall be a root of Jesse, and he that shall rise to reign over the Gentiles; in him shall the Gentiles trust.
The root of Jesse is Jesus, the descendant of Jesse, who rises to reign as ruler over the Gentiles. In him the Gentiles trust and place their hope. The Scriptures reveal God and give this hope through what they teach about Christ, and God's word reveals this hope in the promised ruler.
The Gentiles' trust in this ruler belongs to their inclusion among God's chosen followers, rejoicing together with God's people. Jews who come to faith in Christ are likewise counted as the Israel of God and share in the promised blessing. The verse stands joined to the promise that the God of hope fills believers with joy and peace, so that God's people rejoice and praise him as they come under the Spirit's guidance and into fellowship with Christ.
Trust in him means keeping the eye fixed on him. He never finds fault in order to tear down, but only lays open the perils from which he would deliver. Trusting him calls for guarding the door of the lips, speaking no provoking or faultfinding word, refusing to hear criticism of others, answering harsh provocation with silence, humbling the heart, and confessing sin. It calls for speaking kindly and tenderly, so that refreshing and blessing come to the heart instead of contention and a quarrelsome spirit that shuts one out of the city of God.