Tosefta על נזיר 4:3

In twenty-four matters Beit Shammai was lenient while Beit Hillel was stringent. Beit Shammai says: a person cannot impose a vow on his wife; Beit Hillel says, a man cannot impose a nazirite vow on his son. An egg which was born on a yom tov—others say in the name of Rabbi Eliezer, it and its mother may be eaten. If the one who anointed himself with clean oil and then became unclean went down and immersed himself, Beit Shammai says, even though [the oil] drops and falls, he is clean. Beit Hillel says, [if there remained on him enough] to anoint a small limb, he is unclean, but less than that, he is clean. Rabbi Akiva son of Rabbi Tzadoq said, when I was at Rabbi Yohanan ben Hahironi’s, I saw that he ate his bread dry for they were years of famine. I came and told my father. He said to me, bring him olives. I brought him olives. He took them and looked at them and saw they were wet. He said to me, I don’t eat olives. I came and told my father. He said to me, go tell him the jar is perforated according to Beit Hillel but the dregs have stopped it up. This informs you that he ate in a state of purity, for even though he was a student of Beit Shammai, he acted only according to the words of Beit Hillel.