Walter Marshall, from The Gospel Mystery of Sanctification:
The sure hope of the glory of heaven is made use of ordinarily by God, since the fall of Adam, as an encouragement to the practice of holiness, as the Scripture abundantly shows. Christ, the great pattern of holiness, ‘for the joy that was set before Him, endured the cross, despising the shame’ (Heb. 12:2). And, though I cannot say that the first Adam had such a sure hope, to preserve him in innocency, yet he had, instead of it, the present possession of an earthly paradise and a happy estate in it, which he knew would last, if he continued in holiness, or be changed into a better happiness.
The apostles did not faint under affliction, because they knew that it brought for them ‘a far more exceeding and eternal weight of glory’ (2Cor. 4:16, 17). The believing Hebrews ‘took joyfully the plundering of your goods – knowing in yourselves that you have better and more enduring riches in Heaven’ (Heb. 10:34). The apostle Paul accounts all his sufferings unprofitable, were it not for a glorious resurrection, and that Christians would be of all men most miserable, and that the doctrine of the Epicures were rather to be chosen: ‘Let us eat and drink, for tomorrow we die.’ And he exhorts the Corinthians to be ‘abundant in the work of the Lord, knowing that their labor shall not be in vain in the Lord’ (1Cor. 15:58).
As worldly hope keeps the world at work in their various employments, so God gives His people the hope of His glory to keep them close to His service (Heb. 6:11, 12; 1John 3:3). And it is such a sure hope as shall never make them ashamed (Rom. 5:5). Those that think it below the excellency of their love to work from a hope of the heavenly reward do in this way advance their love beyond the love of the apostles and primitive saints, and even of Christ Himself.