I'm interested in finding references to rapture in the canon, particularly in regard to the fifth anapanasati instruction "He trains himself, 'I will breathe sensitive to rapture.'"
Here is the Piti Sutta, which is one place where 'rapture' is used apart from the anapanasati & jhana pericopes.
"And how is it, bhikkhus, that by protecting oneself one protects others? By the pursuit, development, and cultivation of the four establishments of mindfulness. It is in such a way that by protecting oneself one protects others.
"And how is it, bhikkhus, that by protecting others one protects oneself? By patience, harmlessness, goodwill, and sympathy. It is in such a way that by protecting others one protects oneself.