[The above analogy] is similarly [applicable and it is forbidden to take revenge and bear a grudge against his fellow], if a situation will occur [in which this person] will not do a certain [act of] good to him, which he [had] sought from [this person]. Even [if his fellow were to] cause him pain, and insult him in a given matter, he should [nevertheless] not take revenge and should not bear [any] hatred [within himself] against [this individual. He should not retaliate or hate this person who he feels wronged him], for who is his fellow, and who is he? Everything has emanated from one source, as it is written [in Divrei HaYomim I], “Who is like Your nation Israel, they are one nation in the land” (Divrei HaYomim I: 17; 21), and it is written, “The entire soul that came to the House of Ya’akov…”, (Bireishis: 46; 27) [The above quoted verse] does not write “souls”, [in the plural, in order] to teach us, that, Above, [in Heaven], all the souls of [the Nation of] Israel are as one soul, even though each [person] has their own characteristics. [This] resembles the overall [makeup of the] person, even though, in general, he is one person, however, he [is composed of] primary limbs, such as the head and the heart, [as well as] those [limbs] that are secondary such as the hand and the foot, [each limb serving a unique purpose. In addition], all [of the souls of] Israel, will, in the end, be gathered to one source, that being under [HaShem’s] Throne of Glory. [This follows that which] is stated [in sefer Shmuel, as follows], “and the soul of my master will be bundled in the bundle of life…”, as our Sages of Blessed Memory have said [in maseches Shabbos (152b), see RaSh”I]. Only in this world, as the person is enclothed in his own physicality, and each person’s affairs and actions are specific to him, a person imagines in his mind that he is an individual man, and is not connected at all to his fellow Jew, however, in reality, this is not the case.
 Note from the “Kol HaLashon” Hebrew printing of sefer “Shmiras HaLashon”: [This teaching is found in [maseches] Nidarim: Chapter 9; Halacha 4, also see the commentary “Korban HaEidah” on the gemara.]
The gemara in the Yirushalmi discusses an incident where Rabbi Meir retracted an individuals vow to not financially benefit a specific Jew. He stated, had you known that by vowing against helping this individual you would have transgressed the mitzvos of not bearing a grudge, not taking revenge, loving your fellow Jew as you love yourself, and helping your fellow by allowing him to “live with you” by supporting him, you would not have taken the vow against benefiting him financially.
 From “Kol HaLashon”: This teaching is found in the SMa”G (Sefer Mitzvos Gidolos), positive [mitzvah] 9.
 A similar teaching is found in Vayikra Rabba (Parsha 4, end of sif 6), where Rabbi Yihoshua ben Korchah teaches that the Jewish People are considered as sharing one soul, for we serve the same G-d. However, with regards to Eisav, the Torah writes "souls" in the plural. (Bireishis: 36; 6) The reason for the distinction between the descendants of Ya'akov and the descendants of Eisav is that Eisav's descendants worshipped many "gods".