Genesis 14:23 – Neither from a thread to a shoe strap, nor will I take from whatever is yours, that you should not say, ‘I have made Abram wealthy.’
Gemora Sotah 4b: Rava derived from this verse that as a reward for not taking neither a thread nor a shoe strap Abraham children merited two mitzvot as rewards. For not taking a thread, they merited the blue thread of the tzitzit. For not taking a shoe strap, they merited the straps of tefillin.
Torah Temimah Colloquial Translation on Note #19:
Rashi explains that the reward was due to the fact that Abraham totally avoided [even a hint of] theft. At first glance, this explanation does not seem to make sense. How can this be called a great act by Abraham in just avoiding theft? Also, it is difficult to understand what type of theft is involved here. Lawfully, Avraham was entitled to the spoils of the war. This is in accordance with the general principal that ‘he who saves something from an idol worshipper or from robbers, it is his to keep’. Therefore, it seems that one must say that Abraham refused to take any spoils of the war in order to sanctify God’s name. That being the case, then it would be necessary to return all property, no matter what the circumstances. This is also in accordance with Choshen Mishpat Section 267 – ‘in a place where there is an opportunity to sanctify God’s name, one must return lost property to an idol worshipper even if he has already despaired of ever finding the lost object’. Since Abraham, in this situation, wanted to sanctify God’s name, he was obligated by law to return the spoils of war. This was the action that deserved the reward: since he wanted to sanctify God’s name, he caused an obligation upon himself that could have been avoided.
[The above explanation satisfies and fulfills the comments of Rashi.]
Were it not for Rashi’s comments, it would be possible to explain the merit of Abraham in a different manner, as follows. Abraham won this war in a supernatural means with only 318 soldiers, or as some say with only one soldier – Eliezer. Additionally, as is explained on verse 15, an angel and the stars of the night fought on his behalf. All these point to the fact that Abraham’s victory was a miraculous one. As it notes in Gemora Taanit 24a, it is forbidden to materially benefit from miracles. This then would explain why Abraham merited a reward. From the fact that Abraham refused to benefit from the spoils of the war shows that he attributed the victory not to his own strength and power of his hand, but rather he attributed the victory as a miracle of God. That was why he declined to benefit from the spoils of the war, because one is forbidden to benefit materially from a miracle.
[By the way], note that Rashi and the Rambam disagree on one particular in the law of tzitzit. Rashi’s opinion is that two of the four threads should be blue. The Rambam’s opinion is that only one of the four threads should be blue. Behold, even though one can’t bring clear halachic proofs from aggadic stories, nevertheless, the simple meaning of the phrase ‘Abraham merited the thread of blue’ shines forth supporting the view of the Rambam. This supports the view that, by law, there should only be one thread of blue in the tzitzit.
Regarding Rashi’s view that there are two threads of blue, perhaps Rashi also realized the implication of the phrasing in the verse and the midrash. That would explain why Rashi noted that the thread in the verse alluded, in general, to the commandment of tzitzit. For the Rambam, however, the phraseology is more forcefully specific.
Note also that in the Yalkut and in the Tanchuma this braita is phrased slightly differently: the shoe strap is associated with the shoe of the halitzah ceremony rather than with the strap of tefillin. Perhaps this version of the braita is this way because the author did not feel that a ‘shoe strap’ in the verse aligned well with the ‘strap of tefillin’. (Their only common feature is that they are both made of leather.) On the other hand, the author of our version quoted above did not feel it appropriate to associate the reward with the shoe of halitzah since the shoe of halitzah is essentially used as a punishment. That being the case, it would be unusual to associate that with the idea of something that was given as a reward.
Editor’s Note: I chose this note because of the idea mentioned in the initial section. Since Abraham wanted to sanctify God’s name, he did not accepted even lawful gains from the war. The Torah Temimah notes that we too, if we want to sanctify God’s name, should not act in the strict accordance with the law but rather go beyond the letter of the law.