John Gill

Saying, surely blessing I will bless thee,.... Which is expressive of the certainty of the blessings; the reality and substantiality of them; the abundance of them, and the continuance of the same: and of this nature are all spiritual blessings; as to be chosen of God; to have God to be a covenant God and Father; to be justified, pardoned, adopted, and sanctified, and so have a right and title to eternal happiness: and multiplying I will multiply thee; meaning both in his natural and spiritual seed, which has had its accomplishment.