Albert Barnes Commentary Colossians 1:5

"because of the hope which is laid up for you in the heavens, whereof ye heard before in the word of the truth of the gospel," — Colossians 1:5 (ASV)

For the hope which is laid up for you in heaven. That is, "I give thanks that there is such a hope laid up for you." The evidence which he had that this hope was theirs was founded on the faith and love for the saints which he heard they had shown. He fully believed that where there was such faith and love, there was a well-founded hope of heaven. The word "hope" here is used, as it often is, for the thing hoped for. The object of hope—namely, eternal happiness—was reserved for them in heaven.

Of which you heard before. That is, when the gospel was first preached to you. You were told of the blessed rewards of a life of faith in heaven.

In the word of the truth of the gospel. That is, in the true word of the gospel.