What instruments were used in Proverb by Steve Reich?

In "Proverb" by Steve Reich, the primary instruments used are voices and a small ensemble of instruments, including piano, marimba, and vibraphone. The piece features a minimalist approach, utilizing a repeating musical pattern and phasing techniques. The vocal parts are based on a text by the philosopher Ludwig Wittgenstein, contributing to the piece's intricate interplay between speech and music.