Tosefta untuk Amsal 21:2

Even though Beit Shammai were divided against Beit Hillel regarding rival wives and sisters, and regarding women of doubtful marital status, and regarding old bills of divorce, and regarding one who betroths a woman with the equivalent of a perutah, and regarding [the marital status of] one who divorces his wife and then lodges with her in an inn, Beit Shammai did not refrain from marrying women from Beit Hillel, nor did Beit Hillel from Beit Shammai. Rather, they conducted themselves with truth and peace between them, as it is said (Zech. 8:19), "Love truth and peace." [Similarly,] even though these prohibited and those permitted [in matters of purity], they did not refrain from the preparation of ritually pure foods [using the vessels of the other], to fulfill what is said (Prov. 21:2), "All the ways of a man seem meritorious in his own eyes, but God measures the hearts." Rabbi Shimon says, they would not refrain in matters of doubt; however, [they would refrain] in matters of certainty. The halacha is always according to the words of Beit Hillel. One who desires to be stringent on himself to conduct himself according to the stringencies of Beit Shammai and according to the stringencies of Beit Hillel, concerning him it is said (Ecc. 2:14), "A fool walks in darkness." One who grabs onto the leniencies of Beit Shammai and the leniencies of Beit Hillel is an evildoer; rather if [one conducts himself] according to the words of Beit Shammai, [one does so] according to their leniencies and according to their stringencies, [and] if according to the words of Beit Hillel, [one does so] according to their leniencies and according to their stringencies.