This verse finishes the LORD's question begun in Genesis 18:17: "Shall I hide from Abraham that thing which I do". Genesis 18:18 gives the reason He should not: who Abraham is going to become. The question expects the answer no. Matthew Henry says God here expresses Himself "after the manner of men, with deliberation," and gives two reasons for telling Abraham: he is a friend and favourite, and he will teach his household. Gill calls Abraham "a friend of the Lord" whom God would treat as a friend "by imparting his secrets to him," and adds that Abraham had "a near relation that dwelt there," his nephew Lot. Keil & Delitzsch say the reason was Abraham's calling to be the father of God's people, so that by teaching his descendants he might lead them in righteousness and they would "not be overtaken by judgment."

The LORD answers His own question by going on to explain: "For I know him, that he will command his children and his household after him, and they shall keep the way of the LORD, to do justice and judgment" (Genesis 18:19). Then He does not hide His plan. He tells Abraham, "the cry of Sodom and Gomorrah is great," and "I will go down now, and see" (Genesis 18:20-21). The men go toward Sodom, "but Abraham stood yet before the LORD" (Genesis 18:22), and he begins to plead for the city (Genesis 18:23).

God treats Abraham as someone to be let in on His purposes, not as a bystander. Matthew Henry writes that God "admits him into more intimate communion with himself than ever, as the man of his counsel," and links this to Psalms 25:14: "The secret of the LORD is with them that fear him." Scripture later calls Abraham "the Friend of God" (James 2:23).

The reasons God gives reach far beyond Abraham. He will become a nation through which "all the nations of the earth" will be blessed, and he will teach his household "the way of the LORD, to do justice and judgment" (Genesis 18:18-19). Keil & Delitzsch say the judgment on Sodom was explained to Abraham so it would be "a lesson and a warning to his descendants also." Gill reads "blessed in him" as blessing "in his seed, the Messiah," and Paul says this promise, "In thee shall all nations be blessed," was the gospel preached beforehand to Abraham (Galatians 3:8).