Rabbi Yochanan ben HaChoranit Hosting the House of Hillel and House of Shammai in his Succot-Hut: Berachot 11a; Eruvin 13b
The Students of Shammai and of Hillel meeting in the attic of Rabbi Yochanan ben Betairah: Menachot 41b
How to practice, when there is a disagreement between the house of Hillel and the house of Shammai: Eruvin 6b-7a; Pesachim 114a; Ketuvot 60b
The students of Shammai debated with the students of Hillel for three years, until a Divine Voice announced that although the words of both are the words of the Living Gd, the law follows the students of Hillel, due to their gentle humility: Eruvin 13b
The students of Hillel were so humble that when they disagreed with the students of Shammai, they quoted the opposition opinion first: Eruvin 13b
The opinion of Beit Shammai is as nothing when it conflicts with that of Beit Hillel: Beitzah 11b