(Latin: O sacred banquet) is a short offertory motet for four-part mixed chorus by French composer Olivier Messiaen, setting "O sacrum convivium".

The composition of the motet on a Latin text for the offertory of the mass was commissioned by a clergyman, Abbé Brun, and Messiaen presumably completed it within the first months of 1937, when he was 29.

Messiaen said that four unspecified solo voices could also be a suitable scoring for the piece, along with an optional accompaniment of an organ (ad libitum), which is unusually flexible for him.

[5] The tempo indication at the beginning of the piece is Lent et expressif (Slow and expressive) and performers are asked to count eighth notes, as no time signature is provided (as became usual in future Messiaen compositions).

[8] Some scholars dispute the tonal aspect of the work and offer different explanations based on a system Messiaen later came to call "modes of limited transposition".