Rashi comments that the “apb” which they made in Charan, refers to the many people which Avrom and Sarai had the opportunity to convert.
Avrohom dedicated his life to one goal and purpose – to disseminate Hashem’s truth throughout the world. Wherever he went and whenever the opportunity arose, Avrohom would spread the word of Hashem. His house was open to all so that he might teach and guide more people in the ways of Hashem.
Rabbi Avohu said in the name of Rabbi Eliezer: “Why was Avrohom punished that his children were enslaved in Egypt for 210 years?” Rabbi Yochonon says, “because he held back people from entering under the wings of Hashem, as the posuk says: The king of Sodom told Avrohom give me the people and take the money for yourself.” The Ran comments: “had Avrohom not given up these people to Sodom he would have been able to influence them to convert.” For this he was punished.
This seems to be a great paradox. How is it that a man who devotes his entire life by reaching out to multitudes should be punished so gravely because of one time that he did not fight for these people, and instead allowed them to go to Sodom. Surely Avrohom had a good reason for not making an issue regarding these people with the king of Sodom. Obviously, one whose lifelong goal is reaching out to others should not be punished so severely because of the one time that he was lacking in his fulfillment of this mitzvah.
We learn from Avrohom the awesome responsibility one has to spread the truth in the world. There are no bounds to one’s obligation of proclaiming and publicizing Hashem’s Name in this world. Avrohom left his father’s home and dedicated his life to this goal, and yet for his one failure he was severely punished. Our responsibility in this world is to consistently reach out to our fellow Jews by showing them the ways of Hashem.