Through diligence, Magha, attained the highest state amongst the gods; They praise diligence, negligence is always condemned.
-- DhammaPada Verse 30
A bhikkhu who is devoted to diligence, who sees danger in negligence; Burns away all fetters, both subtle and gross, like a blazing fire that consumes everything.
-- DhammaPada Verse 31
A bhikkhu who is devoted to diligence, who sees danger in negligence; Is incapable of decline, And is near to Nibbāna.
-- DhammaPada Verse 32
The word diligence is a translation of the Pali word appamāda. It can also be translated as heedfulness. The mental quality of wishing to do one's work or duty well and thoroughly, with alertness, with care, and also with gentleness (serenity, tranquility, not agitated, not rushed) is the close approximation of this word.
The quality that is translated as negligence here comes from the Pali word pamāda. It can also be seen as not just gross negligence and carelessness but as anything that deviates one from the mental quality of diligence - rushing to do one's work, losing alertness, and/or losing gentleness.
Whatever wholesome states there are, they are all rooted in diligence, and converge upon diligence (SN 45.140). However, an uninstructed ordinary person, who attaches to any outcomes [in the world] that diligence produces, and then seeing a self in these outcomes, finds himself in the company of mental qualities devoid of diligence.
Related Teachings:
Appamāda sutta - Diligence (SN 3.17) - King Pasenadi asks the Buddha if there is one Dhamma which, having accomplished, secures both kinds of welfare — welfare pertaining to the present life and that pertaining to the next life. The Buddha explains that diligence is that one Dhamma.
Ethics, confidence, diligence precede the eightfold path (SN 46.50 - 54) - As the dawn precedes the sun, ethics, enthusiasm, confidence, right view, and diligence precede the eightfold path.
A Discourse on Eating, Feelings, and Diligence (MN 70) - The Buddha starts out by advising the bhikkhus to eat only during the day, without having a meal at night, explaining the interplay of how pleasant, painful and neither-pleasant-nor-painful feelings can lead to furthering of unwholesome or wholesome states. He then shares on the seven kinds of persons and which kinds must act with diligence. The Buddha concludes by describing how final knowledge is attained gradually.
