על שלשה דברים העולם עומד: על התורה ועל העבודה ועל גמילת חסדים (אבות א:ב)

Shimon Hatzaddik wants to evoke the merits of the three Avos – forefathers.  Even if the world is not worth sustaining, the Avos’ merits are enough to save the world.  This is what the Mishna explains: אל שלשה דברים העולם עומד – the world stands in the merit of the three Avos.

The words על התורה refer to Yakov Avinu, who occupied himself with Torah.

The words על העבודה refer to Yitzchak Avinu since he was willing to sacrifice himself as a Korban.

The words על גמילת חסדים refer to Avraham Avinu, who was the source of Chessed.