For the sake of one righteous man the whole world is preserved in existence, as it is written (Prov. x. 25), "The righteous man is an everlasting foundation."
Yoma, fol. 38, col. 2.
Rabbi Meyer saith, "Great is repentance, because for the sake of one that truly repenteth the whole world is pardoned; as it is written (Hosea xiv. 4), 'I will heal their backsliding, I will love them freely, for mine anger is turned away from him.'" It is not said, "from them," but "from him."
Ibid., fol. 86, col. 2.
He who observes one precept, in addition to those which, as originally laid upon him, he has discharged, shall receive favor from above, and is equal to him who has fulfilled the whole law.
Kiddushin, fol. 39, col. 2.
If any man vow a vow by only one of all the utensils of the altar, he has vowed by the corban, even although he did not mention the word in his oath. Rabbi Yehuda says, "He who swears by the word Jerusalem is as though he had said nothing."
Nedarim, fol. 10, col. 2.
Balaam was lame in one foot and blind in one eye.
Soteh, fol. 10, col. 1, and Sanhedrin, fol. 105, col. 1.