Paṭhamachaphassāyatanasutta

sn35.71:2.1 When he said this, one of the mendicants said to the Buddha,

sn35.71:2.2 “Here, sir, I’m discouraged.

sn35.71:2.3 For I don’t truly understand the six fields of contact’s origin, disappearance, gratification, drawback, and escape.”