“Mendicants, the Ganges river slants, slopes, and inclines to the east. In the same way, a mendicant developing and cultivating the five faculties slants, slopes, and inclines to extinguishment.

How so? It’s when a mendicant develops the faculties of faith, energy, mindfulness, immersion, and wisdom, which culminate in the removal of greed, hate, and delusion. That’s how a mendicant developing and cultivating the five faculties slants, slopes, and inclines to extinguishment.”

To be expanded for each of the different rivers as in SN 45.91-102.

Six on slanting to the east,
and six on slanting to the ocean;
these two sixes make twelve,
and that’s how this chapter is recited.

"Seyyathāpi, bhikkhave, gangā nadī pācīnaninnā pācīnapoṇā pācīnapabbhārā; evameva kho, bhikkhave, bhikkhu pañcindriyāni bhāvento pañcindriyāni bahulīkaronto nibbānaninno hoti nibbānapoṇo nibbāna­pabbhāro.

Kathañca, bhikkhave, bhikkhu pañcindriyāni bhāvento pañcindriyāni bahulīkaronto nibbānaninno hoti nibbānapoṇo nibbāna­pabbhāro? Idha, bhikkhave, bhikkhu saddhindriyaṁ bhāveti rāgavinayapari­yosānaṁ dosavinayapariyosānaṁ mohavinayapariyosānaṁ … pe … paññindriyaṁ bhāveti rāgavinayapari­yosānaṁ dosavinayapariyosānaṁ mohavinayapariyosānaṁ.

Evaṁ kho, bhikkhave, bhikkhu pañcindriyāni bhāvento pañcindriyāni bahulīkaronto nibbānaninno hoti nibbānapoṇo nibbāna­pabbhāro"ti.

Dvādasamaṁ.

Gangāpeyyālavaggo terasamo.

Cha pācīnato ninnā,
cha ninnā ca samuddato;
Dvete cha dvādasa honti,
vaggo tena pavuccatīti.