There is righteousness in God’s rewarding. The Apostle tells us, that he that comes unto God must not only believe that he is, but that he is the rewarder of them that diligently seek him (Heb. 11:6). There is, as our Saviour informs us, a difference of rewards, there is a prophet’s reward, and a righteous man’s reward (Matt. 10:41), i.e. God will reward, but in a different manner, those who shew kindness to either of these. Yea we are told in the same chapter, that he who refreshes a disciple with a cup of cold water, shall be recompensed for it. Whence we may infer, that no good action (be it never so mean) shall go unrewarded. Now, ‘tis plain that God’s justice is shewed in this, for else the Apostle would not have said (Heb. 6:20) God is not unjust to forget the labour of love. And (2 Thess. 1:6) It is a righteous or just thing with God, to recompense to you that are troubled, rest. It is manifest therefore, that God acts according to the laws of justice and righteousness, when he rewards the good services of the faithful in this life. And he doth so when he crowns them with everlasting glory in the mansions of the blessed, as we may gather from 2 Thess. 4:8, There is laid up for me a crown of righteousness, which the Lord the righteous judge shall give me at that day. By the tenor of the New Covenant, there is assured unto all believers eternal happiness, both as God is merciful, and as he is just. That the crown is laid up for them, is the product of divine mercy, that it is actually given to them, at the great day of accounts, argues God to be righteous, for seeing he hath engaged by his promise to bestow heaven upon them, it becomes an act of justice or righteousness to perform his word and promise: though to make this promise to them at first, was an act of mere grace and favour. So that the remunerative justice of God is not to be measured by the rules and proportions of human justice, which is according to men’s merits: but God’s giving a reward to holy men (none of whom are in a capacity to deserve anything at his hands; yea whose daily failings render them obnoxious to him) is to be reckoned as an act of mercifulness and liberality.
– John Edwards (1637-1716), Theologia Reformata, vol. 1 (1713), p. 100-101.