Robert Candlish was a Scottish Presbyterian pastor in the 19th century. He had a major hand in the formation of the Free Church of Scotland. He also wrote several books – one of them being Studies in Genesis. This is an excellent resource on the first book of the Bible. I found his comments on Abraham’s intercession for Sodom and Gomorrah in Genesis 18 to be quite helpful. Here they are in summary and edited form.
1) “There is no intrusive presumption in Abraham’s intercessory pleading; no attempt to pry into the secret things which belong to the Lord our God (Deut. 29:29); no thought of meddling with the purposes or decrees of election, which the Lord reserves exclusively to himself. Abraham does not aspire to any acquaintance with these high and hidden mysteries, nor does he consider that to be necessary in order to his offering such sort of prayer. …[Similarly], why should any of you ever feel yourselves hindered or unrestrained in praying for the unconverted – because you are ignorant of God’s purpose of election respecting them. Does that ignorance prevent you from laboring for their good? Not unless your mind is wholly perverted by unprofitable speculation. …Abraham was as ignorant as you are of the Lord’s eternal decrees, but he laid hold of the things revealed [namely, that God was fair and just] and prayed for the cities.”
2) “Abraham does not base his intercession on his own merit, or any title he may have that would obtain favors for others. He does not ask the Lord, as for his [Abraham’s] sake, to spare or bless those for whom he prays. There is only one intercessor who can do this, namely, the only mediator between God and man, Jesus Christ the righteous. But Abraham claims nothing as he intercedes. Rather, he is dust and ashes. It is by grace alone, and through a righteousness not his own, that he has any footing at all in the favor and friendship of God. But since he has that footing, he comes with boldness and confidence.”
3) “Abraham’s intercession proceeds upon the known character of God, and the known principles of God’s ways. Not claiming to know God’s secret decrees, and not claiming any merit of his own, he has enough warrant to plead with God based on the justice and equity of God and his ways. He knows God as the just God and Savior, and on that twofold knowledge of God he builds his argument. …On this assurance Abraham plants his foot. From this high ground he makes his assault, as it were, knocking at the door of heaven’s mercy….”
4) “Abraham’s intercession was combined with a spirit of entire submission to divine sovereignty. All throughout he is most anxious to disclaim every thought of interfering with the supreme will of God. The growing earnestness and intensity, we might almost say impatience, of his pleading, is tempered by a profound sense of the liberty he is taking, and a salutary fear of offending. Abraham does not forget his position; he is but dust and ashes, while God is the Judge of all the earth. He is sure that God will deal righteously and do right.”
If you’re looking for a good commentary on Genesis – one that is especially helpful in the narratives of Abraham, Isaac, and Jacob – I highly recommend Robert Candlish. The language is a little dated, but with a little effort it is readable. And, it’s only $0.99 on Kindle, so you can use a dictionary quite easily to help you read it.