God is about to bring devastation upon Sodom, but He pauses to share His plans with Abraham. This moment of divine transparency emphasizes the absolute certainty of the promise that Abraham will become a great nation [הכתב והקבלה]. Furthermore, because God is speaking about Abraham in his absence, He naturally attaches a blessing to his name, much like the practice of blessing the memory of the righteous [רש"י, גור אריה].
The primary approach among commentators is that God brings Abraham into His confidence out of deep affection and respect. Because Abraham is destined to be the father of many nations, it is only fitting that God does not hide the way He governs the world from him [רש"י, שד"ל, חזקוני]. Beyond this mutual respect, there is a clear educational and moral purpose. God wants Abraham to teach his children exactly how divine justice operates. By knowing the truth beforehand, Abraham will understand that the destruction of Sodom is not a random natural disaster, but a deliberate punishment for grave sins [רד"ק].
Sharing this secret also serves to protect Abraham's legacy. If God had hidden the plan, future generations might look back and wonder how Abraham could be so cruel as to stand by without praying for his neighbors. By bringing him into the inner circle, God gives him a choice: if there are righteous people in Sodom, Abraham can pray and try to save them. If they are entirely wicked, Abraham will recognize the absolute justice of God's verdict and accept it [רמב"ן, ביאור יש"ר]. Furthermore, this revelation prevents Abraham from experiencing deep personal anguish. Had he not known that his recent guests were angels on a divine mission, he might have mistakenly believed that his own hospitality had drawn robbers and murderers to Sodom, leading him to regret his acts of kindness [שפתי כהן]. Alternatively, he might have fallen into despair, thinking that his personal merits were simply too weak to protect the surrounding area [פרדס יוסף].
The promise that Abraham will become a great and mighty nation is not necessarily a guarantee of massive population size or physical military strength. Instead, it represents a profound spiritual power that will be granted to every single one of his descendants, enabling them to carry the message of goodness and divine instruction to the world [חומש קה"ת]. Through this spiritual strength, Abraham's character will become universally central, and his moral guidance will deeply influence countless nations [ספורנו, ביאור שטיינזלץ].
The nature of how all the nations of the earth will be blessed through him is viewed from two distinct perspectives. The primary approach among commentators is that the nations will actively receive a tangible benefit. The entire world will enjoy abundance and blessing because of Abraham and the protective presence of his descendants, extending even to distant nations that do not inherently deserve such grace on their own merits [אבן עזרא, אור החיים, תורה תמימה]. Conversely, other scholars suggest that the blessing is not merely a flow of physical abundance. Rather, all nations will eventually use Abraham's name as the ultimate standard of success, blessing one another by wishing that God makes them like the nation that descended from him [רלב"ג]. Ultimately, all people will desire to trace their roots back to Abraham and be connected to his legacy [ביאור שטיינזלץ].