Albert Barnes Commentary Acts 20:36

"And when he had thus spoken, he kneeled down and prayed with them all." — Acts 20:36 (ASV)

He kneeled down. The usual attitude of prayer. It is the proper posture of a suppliant. It indicates reverence and humility; and is represented in the Scriptures as the common attitude of devotion (2 Chronicles 6:13; Daniel 6:10; Luke 22:41; Acts 7:60; Acts 9:40; Acts 21:5; Romans 11:4; Philippians 2:10; Ephesians 3:14; Mark 1:40).