Earth Store Bodhisattva vowed:

As long as all the hells are not emptied
I vow not to become a Buddha
Only when all sentient beings are saved
Will I attain Bodhi
(Sutra of the Vows of Earth Store Bodhisattva)

How compassionate Earth Store Bodhisattva was! He vowed to put off his own salvation indefinitely until all sentient beings were saved.