Though the fool fast month after month eating only the tip of a kusa blade, he is not worth a sixteenth part of those who have understood the Dhamma.

Māse māse kusaggena — month after month with the tip of a kusa blade: the image describes the most extreme austerity possible. Kusa (sacred grass, Desmostachya bipinnata) has very fine blade tips; eating from it month after month is the severest fasting imaginable.

Kalaṃ agghati soḷasiṃ — not worth a sixteenth part: the kalā soḷasī was in classical India the smallest fraction used to indicate radical scale differences. No physical austerity, however extreme, equals understanding of the Dhamma.

Saṅkhātadhammānaṃ — of those who have understood the Dhamma: not theoretical Dhamma but the experienced, integrated, lived Dhamma.

This verse is a direct criticism of extreme asceticism as a path in itself. The Buddha himself had practiced severe austerities before abandoning them in favor of the middle way. Understanding the Dhamma surpasses infinitely any external physical feat.