And what, mendicants, is the effort to preserve? It’s when you generate enthusiasm, try, make an effort, exert the mind, and strive so that skillful qualities that have arisen remain, are not lost, but increase, mature, and are fully developed. This is called the effort to preserve. These are the four efforts.

Restraint and giving up, development and preservation: these are the four efforts taught by the Kinsman of the Sun. Any mendicant who keenly applies these may attain the ending of suffering.”

Numbered Discourses 4.70 7. Fitting Deeds Unprincipled