The Torah goes to great lengths to describe the details of the lives of our forefathers because of the moral lessons their actions convey.
Abraham, a man of peace and compassion, did not hesitate to risk his life and go to war against four powerful kings in order to rescue his nephew, despite their falling out.
When he returned victorious from battle together with the possessions that had been taken from the king of Sodom, the king offered it all to Abraham as his reward.
Abraham replied, “I raise my hand as an oath to G-d that I will not take a thing of yours!”
It seems a little extreme for Abraham to take a solemn oath. Why didn’t he simply say “thanks but no thanks”?
The Torah teaches an important code of conduct from Abraham’s actions and a lesson for our lives. When confronted with something we may want but believe we should decline, our first impulse may indeed be to refuse it. Soon afterwards, however, we may begin to recalculate and rethink our initial decision. Perhaps we acted too hastily, after all, there is nothing really wrong in accepting at least part of what we were offered, and there may even be legitimate reasons why we should do so. Within a relatively short period of time our capacity to rationalize produces ingenious arguments why we should really not turn down the offer.
Abraham knew he was right in rejecting the king’s offer, but just a little bit later, he might be tempted to change his mind.
Therefore, he took a solemn oath and bound himself irrevocably to his decision and thereby no longer had to struggle to resist his own rationalizations or outside influences.
~ Rabbi Shaul