Pariyāyasutta

Suttapiṭaka · Saṁyuttanikāya · Mahāvaggasaṁyutta · Vol. 19 · Section 555

[555] Bhikkhus, whatever is dullness (thīna), that too is a hindrance (nīvaraṇa); whatever is drowsiness (middha), that too is a hindrance. Thus it is that this comes into the summary statement as "the hindrance of dullness and drowsiness (thīnamiddha)." By this method of exposition, this becomes twofold.

English translation from the Pali (Siam Raṭṭha edition) — under review, not for citation.