John Gill (1697 – 1771): Matthew 18:21-35 is about chastisement

 John Gill was not a Free Grace theologian, he was a Reformed Baptist. However, when reading his commentary, I noticed an interesting thing, being the fact that Gill took the Free Grace interpretation of this parable: 

 this forgiveness is to be understood of averting calamities and judgments, likely to fall for his iniquities, which is sometimes the sense of this phrase: see ( 1 Kings 8:34 1 Kings 8:36 1 Kings 8:39 ) and so his being delivered to the tormentors may mean, his being distressed with an accusing guilty conscience, an harassing, vexing devil, many misfortunes of life, and temporal calamities. Though after all, this is not strictly to be applied to any particular case or person, but the scope of the parable is to be attended to; which is to enforce mutual forgiveness among men

John Gill’s Exposition of the Bible