The Related Suttas Collection 46.21

3. With Udāyī

To Awakening

Then a bhikkhu went up to the Buddha … and said to him:

“Sir, they speak of the ‘awakening factors’. How are the awakening factors defined?”

“Bhikkhu, they’re called awakening factors because they lead to awakening. A bhikkhu develops the awakening factors of mindfulness, investigation of principles, energy, (mental) joy, tranquility, samādhi, and equanimity, which rely on seclusion, fading away, and cessation, and ripen as letting go. They’re called awakening factors because they lead to awakening.”