Bala samyutta (excerpt)
There are these five strengths. Which five? Strength of conviction, strength of persistence, strength of mindfulness, strength of concentration, & strength of discernment. These are the five strengths. Just as the River Ganges flows to the east, slopes to the east, inclines to the east, in the same way when a monk develops & pursues the five strengths, he flows to Unbinding, slopes to Unbinding, inclines to Unbinding.
There is the case where the monk develops strength of conviction dependent on seclusion, dependent on dispassion, dependent on cessation, resulting in letting go. He develops strength of persistence... mindfulness... concentration... discernment dependent on seclusion... dispassion... cessation, resulting in letting go.