מילון על אבות 1:4

Do not separate yourself from learning Torah wisdom and ethics. Allow yourself to be covered with the dust of the feet of the Sages by following in their footsteps, and you, too, will become wise.

הזוגות – they are those mentioned two-by-two in the first chapter of Mishnah Avot (from Mishnah 4), where two [individuals] received [the tradition] from two [others] [until] from the mouth of Shimon HaTzaddik/the Righteous.