The law of sowing and reaping or giving and receiving in its basic form says what a man sows is what he reaps. This law has its higher variant, in which case a man sows something and God sovereignly determines what harvest comes based on the perceived need of that individual. This higher version came to light when Abraham gave his substance to the visitors. The first thing he got was a new assurance of his wife, Sarah becoming a mother. God had promised him this blessing earlier, but now He attached a time to its fulfillment. One year after that august visit, Sarah became a proud mother of a son. For this couple, the harvest was more than the whole world put together. Then God rewarded Abraham with a revelation. The plight of Sodom was brought to his notice, as well as the coming judgment.
This will connect us to the next thing that Abraham gave. As soon as he heard of the impending doom, Abraham gave himself to intercession for the city and its people. Our passage says he stood before the Lord. This gives us a clear understanding of what intercession means; it is standing before the Lord on behalf of others. Just as he did when he entertained the visitors ever before he knew who they were, he began to intercede for Sodom with no idea of those who lived there apart from Lot and family. Several verses in Genesis 18 detail how Abraham negotiated for souls of men and the destinies of nations. We are called to the same ministry; we are to devote ourselves to the salvation of others.